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Bhattacharya K, Chaudhary N, Bisht P, Satpati B, Manna S, Singh R, Mehta BR, Georgiev YM, Das S. High-Performance Visible-to-SWIR Photodetector Based on the Layered WS 2 Heterojunction with Light-Trapping Pyramidal Black Germanium. ACS APPLIED MATERIALS & INTERFACES 2024; 16:48517-48525. [PMID: 39215749 DOI: 10.1021/acsami.4c08862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
This study presents a layered transition metal dichalcogenide/black germanium (b-Ge) heterojunction photodetector that exhibits superior performance across a broad spectrum of wavelengths spanning from visible (vis) to shortwave infrared (SWIR). The photodetector includes a thin layer of b-Ge, which is created by wet etching of germanium (Ge) wafer to form submicrometer pyramidal structures. On top of this b-Ge layer, the WS2 thin film is deposited using pulsed laser deposition. In comparison to conventional germanium, b-Ge absorbs about 25% more light between 850 and 1750 nm wavelengths. The WS2/b-Ge photodetector has a peak photoresponsivity of 0.65 A/W, which is more than twice the photoresponsivity of the WS2/Ge photodetector at 1540 nm. Additionally, it shows better responsivity and response speed compared with other similar state-of-the-art photodetectors. Such an improvement in the performance of the device is credited to the light-trapping effect enabled by the germanium pyramids. Theoretical simulations employing the finite-difference time-domain technique help validate the concept. This novel photodetector holds promise for efficient detection of light across the vis to SWIR spectrum.
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Affiliation(s)
- Kritika Bhattacharya
- Centre for Applied Research in Electronics, Indian Institute of Technology, Delhi, New Delhi 110016, India
| | - Nahid Chaudhary
- School of Interdisciplinary Research, Indian Institute of Technology, Delhi, New Delhi 110016, India
| | - Prashant Bisht
- Department of Physics, Indian Institute of Technology, Delhi, New Delhi 110016, India
| | - Biswarup Satpati
- Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhannagar, Kolkata 700064, India
| | - Santanu Manna
- Department of Electrical Engineering, Indian Institute of Technology, Delhi, New Delhi 110016, India
| | - Rajendra Singh
- Department of Physics, Indian Institute of Technology, Delhi, New Delhi 110016, India
| | - Bodh Raj Mehta
- Department of Physics, Indian Institute of Technology, Delhi, New Delhi 110016, India
| | - Yordan Marchev Georgiev
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden 01328, Germany
| | - Samaresh Das
- Centre for Applied Research in Electronics, Indian Institute of Technology, Delhi, New Delhi 110016, India
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2
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Surdo S, Barillaro G. Voltage- and Metal-assisted Chemical Etching of Micro and Nano Structures in Silicon: A Comprehensive Review. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2400499. [PMID: 38644330 DOI: 10.1002/smll.202400499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/12/2024] [Indexed: 04/23/2024]
Abstract
Sculpting silicon at the micro and nano scales has been game-changing to mold bulk silicon properties and expand, in turn, applications of silicon beyond electronics, namely, in photonics, sensing, medicine, and mechanics, to cite a few. Voltage- and metal-assisted chemical etching (ECE and MaCE, respectively) of silicon in acidic electrolytes have emerged over other micro and nanostructuring technologies thanks to their unique etching features. ECE and MaCE have enabled the fabrication of novel structures and devices not achievable otherwise, complementing those feasible with the deep reactive ion etching (DRIE) technology, the gold standard in silicon machining. Here, a comprehensive review of ECE and MaCE for silicon micro and nano machining is provided. The chemistry and physics ruling the dissolution of silicon are dissected and similarities and differences between ECE and MaCE are discussed showing that they are the two sides of the same coin. The processes governing the anisotropic etching of designed silicon micro and nanostructures are analyzed, and the modulation of etching profile over depth is discussed. The preparation of micro- and nanostructures with tailored optical, mechanical, and thermo(electrical) properties is then addressed, and their applications in photonics, (bio)sensing, (nano)medicine, and micromechanical systems are surveyed. Eventually, ECE and MaCE are benchmarked against DRIE, and future perspectives are highlighted.
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Affiliation(s)
- Salvatore Surdo
- Dipartimento di Ingegneria dell'Informazione, Università di Pisa, via G. Caruso 16, Pisa, 56122, Italy
| | - Giuseppe Barillaro
- Dipartimento di Ingegneria dell'Informazione, Università di Pisa, via G. Caruso 16, Pisa, 56122, Italy
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Nataraj C, Mohanta K, Badhirappan GP. Investigations on Optical Absorption and the Pyro-phototronic Effect with Selectively Patterned Black Silicon for Advanced Photodetection. ACS APPLIED MATERIALS & INTERFACES 2024. [PMID: 38660705 DOI: 10.1021/acsami.3c18632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
A novel property existing in the stain-etching technique that eliminates the need for expensive etchant masks in the texturization process of silicon wafers was identified. Through the combination of grayscale lithography and stain-etching methodologies, selective patterning of silicon with AR-P 3510 T, a positive-photoresist mask, was carried out. The etch area ratio was varied in nine different patterns of various feature sizes ranging from 400 to 1500 μm. The optical characteristics of the patterned substrates were determined from diffuse reflectance spectroscopy analysis, and the results were supported with finite-difference time-domain simulations. Complimenting the improvement in optical properties, the electrical losses in microwell-patterned photodetector devices have been reduced with an electro-optic optimum value of the surface enhancement factor, γ. The photodetecting efficiency of a selectively patterned microwell photodetector device exceeded the planar and black silicon photodetector devices with a considerable improvement in the pyro-phototronic effect. This work suggests an alternative for black silicon optoelectronic devices providing a new route to fabricate selectively patterned substrates with an achieved detectivity 16- and 20-fold higher than black and planar silicon photodetector devices, respectively.
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Affiliation(s)
- Charumathi Nataraj
- Nanostructured Surfaces and Thin Films Laboratory, Department of Physics, PSG Institute of Advanced Studies, Peelamedu, Coimbatore, Tamil Nadu 641004, India
| | - Kallol Mohanta
- Hybrid Electronics Laboratory, Department of Physics, PSG Institute of Advanced Studies, Peelamedu, Coimbatore, Tamil Nadu 641004, India
| | - Geetha Priyadarshini Badhirappan
- Nanostructured Surfaces and Thin Films Laboratory, Department of Physics, PSG Institute of Advanced Studies, Peelamedu, Coimbatore, Tamil Nadu 641004, India
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4
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Li N, Fratalocchi A. Innovative Strategies for Photons Management on Ultrathin Silicon Solar Cells. GLOBAL CHALLENGES (HOBOKEN, NJ) 2024; 8:2300306. [PMID: 38486928 PMCID: PMC10935887 DOI: 10.1002/gch2.202300306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 11/16/2023] [Indexed: 03/17/2024]
Abstract
Silicon (Si), the eighth most common element in the known universe by mass and widely applied in the industry of electronics chips and solar cells, rarely emerges as a pure element in the Earth's crust. Optimizing its manufacturing can be crucial in the global challenge of reducing the cost of renewable energy modules and implementing sustainable development goals in the future. In the industry of solar cells, this challenge is stimulating studies of ultrathin Si-based architectures, which are rapidly attracting broad attention. Ultrathin solar cells require up to two orders of magnitude less Si than conventional solar cells, and owning to a flexible nature, they are opening applications in different industries that conventional cells do not yet serve. Despite these attractive factors, a difficulty in ultrathin Si solar cells is overcoming the weak light absorption at near-infrared wavelengths. The primary goal in addressing this problem is scaling up cost-effective and innovative textures for anti-reflection and light-trapping with shallower depth junctions, which can offer similar performances to traditional thick modules. This review provides an overview of this area of research, discussing this field both as science and engineering and highlighting present progress and future outlooks.
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Affiliation(s)
- Ning Li
- PRIMALIGHT, Faculty of Electrical and Computer Engineering, Applied Mathematics and Computational ScienceKing Abdullah University of Science and TechnologyThuwal23955‐6900Saudi Arabia
| | - Andrea Fratalocchi
- PRIMALIGHT, Faculty of Electrical and Computer Engineering, Applied Mathematics and Computational ScienceKing Abdullah University of Science and TechnologyThuwal23955‐6900Saudi Arabia
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Chandra A, Ghosh S, Sarkar R, Sarkar S, Chattopadhyay KK. TiO 2 nanorods decorated Si nanowire hierarchical structures for UV light activated photocatalytic application. CHEMOSPHERE 2024; 352:141249. [PMID: 38266878 DOI: 10.1016/j.chemosphere.2024.141249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 01/09/2024] [Accepted: 01/16/2024] [Indexed: 01/26/2024]
Abstract
Water remediation techniques like photolysis have recently piqued the interest of many researchers due to water contamination resulting from heavy industrialization and urbanization. In the current work, as-synthesized TiO2 nanorod decorated vertically aligned silicon nanowire (SiNW) leads to a hierarchical morphological structure formation. The photocatalytic nature of the fabricated SiNW/TiO2 nanoheterojunction is examined by the dye degradation of textile pollutants like methylene blue (MB), rhodamine B (RhB), and eosin B (EB). The catalytic dye degradation investigations revealed that 4 h hydrothermal synthesis of TiO2 on the surface of SiNW (ST4) exhibited excellent catalytic behaviour. In the presence of H2O2 and UV irradiation, the ST4 nanoheterostructure can degrade 98.89% of the model pollutant methylene blue (MB) in 15 min, demonstrating remarkable photocatalytic performance. The direct Z-scheme heterojunction exhibited by the SiNW/TiO2 structure facilitates a more efficient charge transfer mechanism with higher reducing and oxidizing ability leading to enhanced photocatalytic behaviour. The degradation pathway examined by LC-MS studies demonstrated the complete breakdown of the organic MB dye molecules ultimately mineralizing into CO2, H2O, and other inorganic substances. The photocatalyst ST4 exhibited excellent reusability and stability after multiple cycles of dye degradation enabling its use in practical water purification purposes.
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Affiliation(s)
- Ankita Chandra
- School of Materials Science and Nanotechnology, Jadavpur University, Kolkata, 700032, India
| | - Shrabani Ghosh
- School of Materials Science and Nanotechnology, Jadavpur University, Kolkata, 700032, India
| | - Ratna Sarkar
- Thin film and Nano Science Laboratory, Department of Physics, Jadavpur University, Kolkata, 700032, India
| | - Sourav Sarkar
- School of Materials Science and Nanotechnology, Jadavpur University, Kolkata, 700032, India
| | - K K Chattopadhyay
- School of Materials Science and Nanotechnology, Jadavpur University, Kolkata, 700032, India; Thin film and Nano Science Laboratory, Department of Physics, Jadavpur University, Kolkata, 700032, India.
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6
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Wang Q, Yang W, Gao S, Chen W, Tang X, Zhang H, Liu B, Han G, Huang Y. GaN nanowires prepared by Cu-assisted photoelectron-chemical etching. NANOSCALE ADVANCES 2023; 5:2238-2243. [PMID: 37056620 PMCID: PMC10089075 DOI: 10.1039/d2na00889k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Accepted: 03/07/2023] [Indexed: 06/19/2023]
Abstract
A novel Cu-assisted photoelectron-chemical etching is proposed to fabricate GaN nanowires. The functional mechanism of assisted metals, etchant concentrations, and the addition of H2O2 was investigated based on theoretical analysis and experiments. The low-cost metal-assisted etchant (CuSO4) proved more favorable than the conventional noble one (AgNO3) for the preparation of GaN nanowires in this work. The formed Ag dendrite blocked the etching when adopting the Ag-assisted etchant, while the Cu-assisted one did not. Moreover, the etchant consisting of 0.01 M CuSO4 and 5 M HF was demonstrated to realize a relatively good surface morphology and fast etching rate. In addition, the common oxidant H2O2 introduced a quasi-stable configuration between the Cu deposition and dissolution, slowing down the formation of the GaN nanowires. The proposed Cu-assisted photoelectron-chemical etching with the advantages of low cost, room temperature, and controllability could offer a new way to fabricate GaN nano-devices.
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Affiliation(s)
- Qi Wang
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications Chongqing 400065 China
| | - Wen Yang
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications Chongqing 400065 China
| | - Sheng Gao
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications Chongqing 400065 China
| | - Weizhong Chen
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications Chongqing 400065 China
| | - Xiaosheng Tang
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications Chongqing 400065 China
| | - Hongsheng Zhang
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications Chongqing 400065 China
| | - Bin Liu
- School of Electronic Science and Engineering, Nanjing University Nanjing China
| | - Genquan Han
- School of Microelectronics, Xidian University Xi'an China
| | - Yi Huang
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications Chongqing 400065 China
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Wu S, Chen Q, Zhang L, Ren H, Zhou H, Hu L, Tan CS. Wafer-scale nanostructured black silicon with morphology engineering via advanced Sn-assisted dry etching for sensing and solar cell applications. NANOSCALE 2023; 15:4843-4851. [PMID: 36805597 DOI: 10.1039/d2nr06493f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Black-Si (b-Si) providing broadband light antireflection has become a versatile substrate for photodetectors, photo-electric catalysis, sensors, and photovoltaic devices. However, the conventional fabrication methods suffer from single morphology, low yield, or frangibility. In this work, we present a high-yield CMOS-compatible technique to produce 6-inch wafer-scale b-Si with diverse random nanostructures. b-Si is achieved by O2/SF6 plasma-based reactive ion etching (RIE) of the Si wafer which is coated with a GeSn layer. A stable grid of the SnOxFy layer, formed during the initial GeSn etching, acts as a self-assembled hard mask for the formation of subwavelength Si nanostructures. b-Si wafers with diverse surface morphologies, such as the nanopore, nanocone, nanohole, nanohillock, and nanowire were achieved. Furthermore, the responsivity of the b-Si metal-semiconductor-metal (MSM) photodetector in the near-infrared (NIR) wavelength range (1000-1200 nm) is 40-200% higher than that of a planar-Si MSM photodetector with the same level of dark current, which is beneficial for applications in photon detectors, solar cells, and photocatalysis. This work not only demonstrates a new non-lithography method to fabricate wafer-scale b-Si wafers, but may also provide a novel strategy to fabricate other nanostructured surface materials (e.g., Ge or III-V based compounds) with morphology engineering.
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Affiliation(s)
- Shaoteng Wu
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798.
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, P.R. China
| | - Qimiao Chen
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798.
| | - Lin Zhang
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798.
| | - Huixue Ren
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, P.R. China
| | - Hao Zhou
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798.
| | - Liangxing Hu
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798.
| | - Chuan Seng Tan
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798.
- Institute of Microelectronics, A*STAR, 117685, Singapore
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8
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Duan W, Zhi H, Keefe DW, Gao B, LeFevre GH, Toor F. Sensitive and Specific Detection of Estrogens Featuring Doped Silicon Nanowire Arrays. ACS OMEGA 2022; 7:47341-47348. [PMID: 36570182 PMCID: PMC9774403 DOI: 10.1021/acsomega.1c00210] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 11/21/2022] [Indexed: 05/31/2023]
Abstract
Estrogens and estrogen-mimicking compounds in the aquatic environment are known to cause negative impacts to both ecosystems and human health. In this initial proof-of-principle study, we developed a novel vertically oriented silicon nanowire (vSiNW) array-based biosensor for low-cost, highly sensitive and selective detection of estrogens. The vSiNW arrays were formed using an inexpensive and scalable metal-assisted chemical etching (MACE) process. A vSiNW array-based p-n junction diode (vSiNW-diode) transducer design for the biosensor was used and functionalized via 3-aminopropyltriethoxysilane (APTES)-based silane chemistry to bond estrogen receptor-alpha (ER-α) to the surface of the vSiNWs. Following receptor conjugation, the biosensors were exposed to increasing concentrations of estradiol (E2), resulting in a well-calibrated sensor response (R 2 ≥ 0.84, 1-100 ng/mL concentration range). Fluorescence measurements quantified the distribution of estrogen receptors across the vSiNW array compared to planar Si, indicating an average of 7 times higher receptor presence on the vSiNW array surface. We tested the biosensor's target selectivity by comparing it to another estrogen (estrone [E1]) and an androgen (testosterone), where we measured a high positive electrical biosensor response after E1 exposure and a minimal response after testosterone. The regeneration capacity of the biosensor was tested following three successive rinses with phosphate buffer solution (PBS) between hormone exposure. Traditional horizontally oriented Si NW field effect transistor (hSiNW-FET)-based biosensors report electrical current changes at the nanoampere (nA) level that require bulky and expensive measurement equipment making them unsuitable for field measurements, whereas the reported vSiNW-diode biosensor exhibits current changes in the microampere (μA) range, demonstrating up to 100-fold electrical signal amplification, thus enabling sensor signal measurement using inexpensive electronics. The highly sensitive and specific vSiNW-diode biosensor developed here will enable the creation of low-cost, portable, field-deployable biosensors that can detect estrogenic compounds in waterways in real-time.
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Affiliation(s)
- Wenqi Duan
- Department
of Electrical and Computer Engineering, University of Iowa, 205 North Madison Street, Iowa City, Iowa 52242, United States
- Iowa
Technology Institute, University of Iowa, 330 South Madison Street, Iowa City, Iowa 52242, United States
| | - Hui Zhi
- Department
of Civil and Environmental Engineering, University of Iowa, 4105 Seamans Center, Iowa City, Iowa 52242, United
States
- IIHR−Hydroscience
& Engineering, 100
C. Maxwell Stanley Hydraulics Laboratory, Iowa
City, Iowa 52242, United States
| | - Daniel W. Keefe
- Department
of Electrical and Computer Engineering, University of Iowa, 205 North Madison Street, Iowa City, Iowa 52242, United States
- Iowa
Technology Institute, University of Iowa, 330 South Madison Street, Iowa City, Iowa 52242, United States
| | - Bingtao Gao
- Department
of Electrical and Computer Engineering, University of Iowa, 205 North Madison Street, Iowa City, Iowa 52242, United States
- Iowa
Technology Institute, University of Iowa, 330 South Madison Street, Iowa City, Iowa 52242, United States
| | - Gregory H. LeFevre
- Department
of Civil and Environmental Engineering, University of Iowa, 4105 Seamans Center, Iowa City, Iowa 52242, United
States
- IIHR−Hydroscience
& Engineering, 100
C. Maxwell Stanley Hydraulics Laboratory, Iowa
City, Iowa 52242, United States
| | - Fatima Toor
- Department
of Electrical and Computer Engineering, University of Iowa, 205 North Madison Street, Iowa City, Iowa 52242, United States
- Iowa
Technology Institute, University of Iowa, 330 South Madison Street, Iowa City, Iowa 52242, United States
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Gao B, Rojas Chavez AA, Malkawi WI, Keefe DW, Smith R, Haim H, Salem AK, Toor F. Sensitive detection of SARS-CoV-2 spike protein using vertically-oriented silicon nanowire array-based biosensor. SENSING AND BIO-SENSING RESEARCH 2022; 36:100487. [PMID: 35340912 PMCID: PMC8937609 DOI: 10.1016/j.sbsr.2022.100487] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 02/23/2022] [Accepted: 03/18/2022] [Indexed: 11/06/2022] Open
Abstract
The COVID-19 pandemic has caused tremendous damage to the world. In order to quickly and accurately diagnose the virus and contain the spread, there is a need for rapid, sensitive, accurate, and cost-effective SARS-CoV-2 biosensors. In this paper, we report on a novel biosensor based on angiotensin converting enzyme 2 (ACE-2)-conjugated vertically-oriented silicon nanowire (vSiNW) arrays that can detect the SARS-CoV-2 spike protein with high sensitivity and selectivity relative to negative controls. First, we demonstrate the efficacy of using ACE-2 receptor to detect the SARS-CoV-2 spike protein via a capture assay test, which confirms high specificity of ACE-2 against the mock protein, and high affinity between the spike and ACE-2. We then report on results for ACE-2-conjugated vSiNW arrays where the biosensor device architecture is based on a p-n junction transducer. We confirm via analytical modeling that the transduction mechanism of the biosensor involves induced surface charge depletion of the vSiNWs due to negative electrostatic surface potential induced by the spike protein after binding with ACE-2. This vSiNW surface charge modulation is measured via current-voltage characteristics of the functionalized biosensor. Calibrated concentration dependent electrical response of the vSiNW sensor confirms the limit-of-detection for virus spike concentration of 100 ng/ml (or 575 pM). The vSiNW sensor also exhibits highly specific response to the spike protein with respect to negative controls, offering a promising point-of-care detection method for SARS-CoV-2.
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Jin Z, Liu Y, Xia N, Guo X, Hong Z, Zhang H, Yang D. Wet Etching in β-Ga2O3 Bulk Single Crystal. CrystEngComm 2022. [DOI: 10.1039/d1ce01499d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Beta-phase gallium oxide (β-Ga2O3) bulk single crystal has received increasing attentions due to their fantastic performances and widespread use in power devices and solar-blind photodetectors. Wet etching has proved to...
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11
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Wang Q, Zhou K, Zhao S, Yang W, Zhang H, Yan W, Huang Y, Yuan G. Metal-Assisted Chemical Etching for Anisotropic Deep Trenching of GaN Array. NANOMATERIALS 2021; 11:nano11123179. [PMID: 34947528 PMCID: PMC8704282 DOI: 10.3390/nano11123179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 11/20/2021] [Accepted: 11/21/2021] [Indexed: 12/03/2022]
Abstract
Realizing the anisotropic deep trenching of GaN without surface damage is essential for the fabrication of GaN-based devices. However, traditional dry etching technologies introduce irreversible damage to GaN and degrade the performance of the device. In this paper, we demonstrate a damage-free, rapid metal-assisted chemical etching (MacEtch) method and perform an anisotropic, deep trenching of a GaN array. Regular GaN microarrays are fabricated based on the proposed method, in which CuSO4 and HF are adopted as etchants while ultraviolet light and Ni/Ag mask are applied to catalyze the etching process of GaN, reaching an etching rate of 100 nm/min. We comprehensively explore the etching mechanism by adopting three different patterns, comparing a Ni/Ag mask with a SiN mask, and adjusting the etchant proportion. Under the catalytic role of Ni/Ag, the GaN etching rate nearby the metal mask is much faster than that of other parts, which contributes to the formation of deep trenches. Furthermore, an optimized etchant is studied to restrain the disorder accumulation of excessive Cu particles and guarantee a continuous etching result. Notably, our work presents a novel low-cost MacEtch method to achieve GaN deep etching at room temperature, which may promote the evolution of GaN-based device fabrication.
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Affiliation(s)
- Qi Wang
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China; (Q.W.); (K.Z.); (W.Y.); (H.Z.); (W.Y.)
| | - Kehong Zhou
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China; (Q.W.); (K.Z.); (W.Y.); (H.Z.); (W.Y.)
| | - Shuai Zhao
- State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China;
- College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wen Yang
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China; (Q.W.); (K.Z.); (W.Y.); (H.Z.); (W.Y.)
| | - Hongsheng Zhang
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China; (Q.W.); (K.Z.); (W.Y.); (H.Z.); (W.Y.)
| | - Wensheng Yan
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China; (Q.W.); (K.Z.); (W.Y.); (H.Z.); (W.Y.)
| | - Yi Huang
- School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China; (Q.W.); (K.Z.); (W.Y.); (H.Z.); (W.Y.)
- Correspondence: (Y.H.); (G.Y.)
| | - Guodong Yuan
- State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China;
- College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
- Correspondence: (Y.H.); (G.Y.)
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Zhang Z, Liu G, Wang K. Fabrication of Needle-Like Silicon Nanowires by Using a Nanoparticles-Assisted Bosch Process for Both High Hydrophobicity and Anti-Reflection. MICROMACHINES 2021; 12:1009. [PMID: 34577653 PMCID: PMC8471489 DOI: 10.3390/mi12091009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 08/16/2021] [Accepted: 08/23/2021] [Indexed: 01/23/2023]
Abstract
In this work, a modified Bosch etching process is developed to create silicon nanowires. Au nanoparticles (NPs) formed by magnetron sputtering film deposition and thermal annealing were employed as the hard mask to achieve controllable density and high aspect ratios. Such silicon nanowire exhibits the excellent anti-reflection ability of a reflectance value of below 2% within a broad light wave range between 220 and 1100 nm. In addition, Au NPs-induced surface plasmons significantly enhance the near-unity anti-reflection characteristics, achieving a reflectance below 3% within the wavelength range of 220 to 2600 nm. Furthermore, the nanowire array exhibits super-hydrophobic behavior with a contact angle over ~165.6° without enforcing any hydrophobic chemical treatment. Such behavior yields in water droplets bouncing off the surface many times. These properties render this silicon nanowire attractive for applications such as photothermal, photocatalysis, supercapacitor, and microfluidics.
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Affiliation(s)
- Zengxing Zhang
- Department of microsystems, University of South-Eastern Norway, 3184 Horten, Norway;
| | - Guohua Liu
- Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization, North China Electric Power University, Beijing 102206, China;
| | - Kaiying Wang
- Department of microsystems, University of South-Eastern Norway, 3184 Horten, Norway;
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Kolasinski KW. Metal-Assisted Catalytic Etching (MACE) for Nanofabrication of Semiconductor Powders. MICROMACHINES 2021; 12:776. [PMID: 34209231 PMCID: PMC8304928 DOI: 10.3390/mi12070776] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Revised: 06/28/2021] [Accepted: 06/29/2021] [Indexed: 12/31/2022]
Abstract
Electroless etching of semiconductors has been elevated to an advanced micromachining process by the addition of a structured metal catalyst. Patterning of the catalyst by lithographic techniques facilitated the patterning of crystalline and polycrystalline wafer substrates. Galvanic deposition of metals on semiconductors has a natural tendency to produce nanoparticles rather than flat uniform films. This characteristic makes possible the etching of wafers and particles with arbitrary shape and size. While it has been widely recognized that spontaneous deposition of metal nanoparticles can be used in connection with etching to porosify wafers, it is also possible to produced nanostructured powders. Metal-assisted catalytic etching (MACE) can be controlled to produce (1) etch track pores with shapes and sizes closely related to the shape and size of the metal nanoparticle, (2) hierarchically porosified substrates exhibiting combinations of large etch track pores and mesopores, and (3) nanowires with either solid or mesoporous cores. This review discussed the mechanisms of porosification, processing advances, and the properties of the etch product with special emphasis on the etching of silicon powders.
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Affiliation(s)
- Kurt W Kolasinski
- Department of Chemistry, West Chester University, West Chester, PA 19383, USA
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15
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Tamarov K, Kiviluoto R, Swanson JD, Unger BA, Ernst AT, Aindow M, Riikonen J, Lehto VP, Kolasinski KW. Low-Load Metal-Assisted Catalytic Etching Produces Scalable Porosity in Si Powders. ACS APPLIED MATERIALS & INTERFACES 2020; 12:48969-48981. [PMID: 33052667 DOI: 10.1021/acsami.0c13980] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The recently discovered low-load metal-assisted catalytic etching (LL-MACE) creates nanostructured Si with controllable and variable characteristics that distinguish this technique from the conventional high-load variant. LL-MACE employs 150 times less metal catalyst and produces porous Si instead of Si nanowires. In this work, we demonstrate that some of the features of LL-MACE cannot be explained by the present understanding of MACE. With mechanistic insight derived from extensive experimentation, it is demonstrated that (1) the method allows the use of not only Ag, Pd, Pt, and Au as metal catalysts but also Cu and (2) judicious combinations of process parameters such as the type of metal, Si doping levels, and etching temperatures facilitate control over yield (0.065-88%), pore size (3-100 nm), specific surface area (20-310 m2·g-1), and specific pore volume (0.05-1.05 cm3·g-1). The porous structure of the product depends on the space-charge layer, which is controlled by the Si doping and the chemical identity of the deposited metal. The porous structure was also dependent on the dynamic structure of the deposited metal. A distinctive comet-like structure of metal nanoparticles was observed after etching with Cu, Ag, Pd, and, in some cases, Pt; this structure consisted of 10-50 nm main particles surrounded by smaller (<5 nm) nanoparticles. With good scalability and precise control of structural properties, LL-MACE facilitates Si applications in photovoltaics, energy storage, biomedicine, and water purification.
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Affiliation(s)
- Konstantin Tamarov
- Department of Applied Physics, University of Eastern Finland, 70210 Kuopio, Finland
| | - Riku Kiviluoto
- Department of Applied Physics, University of Eastern Finland, 70210 Kuopio, Finland
| | - Joseph D Swanson
- Department of Chemistry, West Chester University, West Chester, Pennsylvania 19383-2115, United States
| | - Bret A Unger
- Department of Chemistry, West Chester University, West Chester, Pennsylvania 19383-2115, United States
| | - Alexis T Ernst
- Department of Materials Science and Engineering, Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269-3136, United States
| | - Mark Aindow
- Department of Materials Science and Engineering, Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269-3136, United States
| | - Joakim Riikonen
- Department of Applied Physics, University of Eastern Finland, 70210 Kuopio, Finland
| | - Vesa-Pekka Lehto
- Department of Applied Physics, University of Eastern Finland, 70210 Kuopio, Finland
| | - Kurt W Kolasinski
- Department of Chemistry, West Chester University, West Chester, Pennsylvania 19383-2115, United States
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16
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Franz M, Junghans R, Schmitt P, Szeghalmi A, Schulz SE. Wafer-level integration of self-aligned high aspect ratio silicon 3D structures using the MACE method with Au, Pd, Pt, Cu, and Ir. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2020; 11:1439-1449. [PMID: 33029473 PMCID: PMC7522463 DOI: 10.3762/bjnano.11.128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 08/14/2020] [Indexed: 06/11/2023]
Abstract
The wafer-level integration of high aspect ratio silicon nanostructures is an essential part of the fabrication of nanodevices. Metal-assisted chemical etching (MACE) is a promising low-cost and high-volume technique for the generation of vertically aligned silicon nanowires. Noble metal nanoparticles were used to locally etch the silicon substrate. This work demonstrates a bottom-up self-assembly approach for noble metal nanoparticle formation and the subsequent silicon wet etching. The macroscopic wafer patterning has been done by using a poly(methyl methacrylate) masking layer. Different metals (Au, Pt, Pd, Cu, and Ir) were investigated to derive a set of technologies as platform for specific applications. Especially, the shape of the 3D structures and the resulting reflectance have been investigated. The Si nanostructures fabricated using Au nanoparticles show a perfect light absorption with a reflectance below 0.3%. The demonstrated technology can be integrated into common fabrication processes for microelectromechanical systems.
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Affiliation(s)
- Mathias Franz
- Nano Device Technologies, Fraunhofer Institute for Electronic Nano Systems ENAS, Technologie-Campus 3, 09126 Chemnitz, Germany
| | - Romy Junghans
- Nano Device Technologies, Fraunhofer Institute for Electronic Nano Systems ENAS, Technologie-Campus 3, 09126 Chemnitz, Germany
| | - Paul Schmitt
- Fraunhofer Institute for Applied Optics and Precision Engineering IOF, Center of Excellence in Photonics, Albert-Einstein-Straße 7, 07745 Jena, Germany
- Institute of Applied Physics, Friedrich-Schiller-University Jena, Albert-Einstein-Straße 15, 07745 Jena, Germany
| | - Adriana Szeghalmi
- Fraunhofer Institute for Applied Optics and Precision Engineering IOF, Center of Excellence in Photonics, Albert-Einstein-Straße 7, 07745 Jena, Germany
- Institute of Applied Physics, Friedrich-Schiller-University Jena, Albert-Einstein-Straße 15, 07745 Jena, Germany
| | - Stefan E Schulz
- Nano Device Technologies, Fraunhofer Institute for Electronic Nano Systems ENAS, Technologie-Campus 3, 09126 Chemnitz, Germany
- Center for Microtechnologies, Chemnitz University of Technology, Straße der Nationen 62, 09111 Chemnitz, Germany
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17
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More-Chevalier J, Novotný M, Hruška P, Fekete L, Fitl P, Bulíř J, Pokorný P, Volfová L, Havlová Š, Vondráček M, Lančok J. Fabrication of black aluminium thin films by magnetron sputtering. RSC Adv 2020; 10:20765-20771. [PMID: 35517742 PMCID: PMC9054304 DOI: 10.1039/d0ra00866d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 05/04/2020] [Indexed: 11/21/2022] Open
Abstract
Black aluminium thin films were prepared by direct current (DC) pulsed magnetron sputtering. The N2 concentration in the Ar–N2 mixture that was used as the deposition atmosphere was varied from 0 to 10%, and its impact on the film growth and optical properties was studied. A strong change in the film growth process was observed as a function of the N2 concentration. At a specific N2 concentration of ∼6%, the Al film growth process favoured the formation of a moth-eye-like antireflective surface. This surface morphology, which was similar to the structure of a cauliflower, is known to trap incident light, resulting in films with a very low reflectivity. A diffuse reflectivity lower than 4% was reached in the ultraviolet-visible-near infrared (UV-VIS-NIR) spectral range that corresponds to a value observed for an ultrahigh absorber. We found that for the preparation of black aluminium, the nitrogen content plays an important role in film formation and the resulting film morphology. A black aluminium film deposited by magnetron sputtering showed a high correlation of diffuse reflectivity with surface morphology and nitrogen content in plasma.![]()
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Affiliation(s)
- J More-Chevalier
- Institute of Physics of the Czech Academy of Sciences Na Slovance 1999/2 182 21 Prague Czech Republic
| | - M Novotný
- Institute of Physics of the Czech Academy of Sciences Na Slovance 1999/2 182 21 Prague Czech Republic
| | - P Hruška
- Institute of Physics of the Czech Academy of Sciences Na Slovance 1999/2 182 21 Prague Czech Republic .,Faculty of Mathematics and Physics, Charles University Ke Karlovu 3 12116 Praha 2 Czech Republic
| | - L Fekete
- Institute of Physics of the Czech Academy of Sciences Na Slovance 1999/2 182 21 Prague Czech Republic
| | - P Fitl
- Institute of Physics of the Czech Academy of Sciences Na Slovance 1999/2 182 21 Prague Czech Republic .,Department of Physics and Measurements, University of Chemistry and Technology Prague Technicka 5 16628 Praha 6 Czech Republic
| | - J Bulíř
- Institute of Physics of the Czech Academy of Sciences Na Slovance 1999/2 182 21 Prague Czech Republic
| | - P Pokorný
- Institute of Physics of the Czech Academy of Sciences Na Slovance 1999/2 182 21 Prague Czech Republic
| | - L Volfová
- Institute of Physics of the Czech Academy of Sciences Na Slovance 1999/2 182 21 Prague Czech Republic .,Faculty of Science, Charles University Hlavova 2030/8 12843 Praha 2 Czech Republic
| | - Š Havlová
- Institute of Physics of the Czech Academy of Sciences Na Slovance 1999/2 182 21 Prague Czech Republic .,Department of Physics and Measurements, University of Chemistry and Technology Prague Technicka 5 16628 Praha 6 Czech Republic
| | - M Vondráček
- Institute of Physics of the Czech Academy of Sciences Na Slovance 1999/2 182 21 Prague Czech Republic
| | - J Lančok
- Institute of Physics of the Czech Academy of Sciences Na Slovance 1999/2 182 21 Prague Czech Republic
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18
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Romano L, Kagias M, Vila-Comamala J, Jefimovs K, Tseng LT, Guzenko VA, Stampanoni M. Metal assisted chemical etching of silicon in the gas phase: a nanofabrication platform for X-ray optics. NANOSCALE HORIZONS 2020; 5:869-879. [PMID: 32100775 DOI: 10.1039/c9nh00709a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
High aspect ratio nanostructuring requires high precision pattern transfer with highly directional etching. In this work, we demonstrate the fabrication of structures with ultra-high aspect ratios (up to 10 000 : 1) in the nanoscale regime (down to 10 nm) by platinum assisted chemical etching of silicon in the gas phase. The etching gas is created by a vapour of water diluted hydrofluoric acid and a continuous air flow, which works both as an oxidizer and as a gas carrier for reactive species. The high reactivity of platinum as a catalyst and the formation of platinum silicide to improve the stability of the catalyst pattern allow a controlled etching. The method has been successfully applied to produce straight nanowires with section size in the range of 10-100 nm and length of hundreds of micrometres, and X-ray optical elements with feature sizes down to 10 nm and etching depth in the range of tens of micrometres. This work opens the possibility of a low cost etching method for stiction-sensitive nanostructures and a large range of applications where silicon high aspect ratio nanostructures and high precision of pattern transfer are required.
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Affiliation(s)
- Lucia Romano
- Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
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Li F, Li Y, Zhuo Q, Zhou D, Zhao Y, Zhao Z, Wu X, Shan Y, Sun L. Electroless Plating of NiFeP Alloy on the Surface of Silicon Photoanode for Efficient Photoelectrochemical Water Oxidation. ACS APPLIED MATERIALS & INTERFACES 2020; 12:11479-11488. [PMID: 32056436 DOI: 10.1021/acsami.9b19418] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
N-type silicon is a kind of semiconductor with a narrow band gap that has been reported as an outstanding light-harvesting material for photoelectrochemical (PEC) reactions. Decorating a thin catalyst layer on the n-type silicon surface can provide a direct and effective route toward PEC water oxidation. However, most of catalyst immobilization methods for reported n-type silicon photoanodes have been based on energetically demanding, time-consuming, and high-cost processes. Herein, a high-performance NiFeP alloy (NiFeP)-decorated n-type micro-pyramid silicon array (n-Si) photoanode (NiFeP/n-Si) was prepared by a fast and low-cost electroless deposition method for light-driven water oxidation reaction. The saturated photocurrent density of NiFeP/n-Si can reach up to ∼40 mA cm-2, and a photocurrent density of 15.5 mA cm-2 can be achieved at 1.23 VRHE under light illumination (100 mW cm-2, AM1.5 filter), which is one of the most promising silicon-based photoanodes to date. The kinetic studies showed that the NiFeP on the silicon photoanodes could significantly decrease the interfacial charge recombination between the n-type silicon surface and electrolyte.
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Affiliation(s)
- Fusheng Li
- State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Institute for Energy Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Yingzheng Li
- State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Institute for Energy Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Qiming Zhuo
- State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Institute for Energy Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Dinghua Zhou
- State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Institute for Energy Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Yilong Zhao
- State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Institute for Energy Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Ziqi Zhao
- State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Institute for Energy Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Xiujuan Wu
- State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Institute for Energy Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Yu Shan
- State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Institute for Energy Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Licheng Sun
- State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Institute for Energy Science and Technology, Dalian University of Technology, Dalian 116024, China
- Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm 10044, Sweden
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20
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Sarkar A, Mukherjee S, Das AK, Ray SK. Photoresponse characteristics of MoS 2 QDs/Si nanocone heterojunctions utilizing geometry controlled light trapping mechanism in black Si. NANOTECHNOLOGY 2019; 30:485202. [PMID: 31426032 DOI: 10.1088/1361-6528/ab3c9f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A unique light trapping mechanism associated with nano-conical textured black Si templates has been utilized to achieve improved photoresponse in MoS2QDs/Si heterojunctions over a wide wavelength range from visible to near infrared. Black Si templates have been fabricated by a simple and cost effective metal assisted chemical etching technique followed by spin-coating of colloidal MoS2 quantum dots (QDs) to form the heterojunction. A peak responsivity of as high as ∼1.39 A W-1 at ∼665 nm for a bias of 5 V has been achieved. The responsivity value is higher as compared to recently published results having similar device structure. The combination of MoS2 QDs and black Si has resulted in a broader spectral response with enhanced optical absorption in the nano-conical heterojunction devices. Finite element based optical simulation results revealed the superiority of MoS2 QDs/Si nano-conical heterojunctions due to improved light trapping. The results appear attractive for next generation Si CMOS compatible broad band photodetectors using two dimensional semiconductors.
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Affiliation(s)
- Arijit Sarkar
- Advanced Technology Development Center, Indian Institute of Technology, Kharagpur-721302, India
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21
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Gu Z, Kothary P, Sun CH, Gari A, Zhang Y, Taylor C, Jiang P. Evaporation-Induced Hierarchical Assembly of Rigid Silicon Nanopillars Fabricated by a Scalable Two-Level Colloidal Lithography Approach. ACS APPLIED MATERIALS & INTERFACES 2019; 11:40461-40469. [PMID: 31588737 DOI: 10.1021/acsami.9b12388] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Periodic arrays of silicon nanowires/nanopillars are of great technological importance in developing novel electrical, optical, biosensing, and electromechanical devices. Here, we report a novel two-level colloidal lithography technology for making periodic arrays of single-crystalline silicon nanopillars (or nanocolumns) over large areas. Spin-coated monolayer silica colloidal crystals with unusual nonclose-packed structures are utilized as first-level etching masks in generating ordered polymer posts whose sizes can be much smaller than the templating silica microspheres. These polymer posts can then be used as second-level structural templates in fabricating highly ordered silicon nanopillars with broadly tunable geometries by employing metal-assisted chemical etching. As the silicon nanopillars are produced by direct wet etching on the surface of a single-crystalline silicon wafer, they are relatively free of volume defects and thus their bending strength approaches the predicted theoretical maximum. Most importantly, the unique nonclose-packed structure of the original colloidal template and the close-to-ideal mechanical property enables the formation of unusual open-structured hierarchical assemblies of rigid silicon nanopillars during water evaporation. Both experiments and numerical finite-difference time-domain modeling confirm the importance of high aspect ratios of the templated silicon nanopillars in achieving superior broadband antireflection properties. The large fraction of entrapped air in the hierarchically assembled silicon nanopillars further facilitates to accomplish superhydrophobic surface states, promising for developing self-cleaning antireflection coatings for many important optoelectronic applications.
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Kolasinski KW, Unger BA, Ernst AT, Aindow M. Crystallographically Determined Etching and Its Relevance to the Metal-Assisted Catalytic Etching (MACE) of Silicon Powders. Front Chem 2019; 6:651. [PMID: 30701171 PMCID: PMC6343677 DOI: 10.3389/fchem.2018.00651] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 12/13/2018] [Indexed: 02/04/2023] Open
Abstract
Metal-assisted catalytic etching (MACE) using Ag nanoparticles as catalysts and H2O2 as oxidant has been performed on single-crystal Si wafers, single-crystal electronics grade Si powders, and polycrystalline metallurgical grade Si powders. The temperature dependence of the etch kinetics has been measured over the range 5-37°C. Etching is found to proceed preferentially in a 〈001〉 direction with an activation energy of ~0.4 eV on substrates with (001), (110), and (111) orientations. A quantitative model to explain the preference for etching in the 〈001〉 direction is developed and found to be consistent with the measured activation energies. Etching of metallurgical grade powders produces particles, the surfaces of which are covered primarily with porous silicon (por-Si) in the form of interconnected ridges. Silicon nanowires (SiNW) and bundles of SiNW can be harvested from these porous particles by ultrasonic agitation. Analysis of the forces acting between the metal nanoparticle catalyst and the Si particle demonstrates that strongly attractive electrostatic and van der Waals interactions ensure that the metal nanoparticles remain in intimate contact with the Si particles throughout the etch process. These attractive forces draw the catalyst toward the interior of the particle and explain why the powder particles are etched equivalently on all the exposed faces.
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Affiliation(s)
- Kurt W Kolasinski
- Department of Chemistry, West Chester University, West Chester, PA, United States
| | - Bret A Unger
- Department of Chemistry, West Chester University, West Chester, PA, United States
| | - Alexis T Ernst
- Department of Materials Science and Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT, United States
| | - Mark Aindow
- Department of Materials Science and Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT, United States
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23
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Economic Advantages of Dry-Etched Black Silicon in Passivated Emitter Rear Cell (PERC) Photovoltaic Manufacturing. ENERGIES 2018. [DOI: 10.3390/en11092337] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Industrial Czochralski silicon (Cz-Si) photovoltaic (PV) efficiencies have routinely reached >20% with the passivated emitter rear cell (PERC) design. Nanostructuring silicon (black-Si) by dry-etching decreases surface reflectance, allows diamond saw wafering, enhances metal gettering, and may prevent power conversion efficiency degradation under light exposure. Black-Si allows a potential for >20% PERC cells using cheaper multicrystalline silicon (mc-Si) materials, although dry-etching is widely considered too expensive for industrial application. This study analyzes this economic potential by comparing costs of standard texturized Cz-Si and black mc-Si PERC cells. Manufacturing sequences are divided into steps, and costs per unit power are individually calculated for all different steps. Baseline costs for each step are calculated and a sensitivity analysis run for a theoretical 1 GW/year manufacturing plant, combining data from literature and industry. The results show an increase in the overall cell processing costs between 15.8% and 25.1% due to the combination of black-Si etching and passivation by double-sided atomic layer deposition. Despite this increase, the cost per unit power of the overall PERC cell drops by 10.8%. This is a significant cost saving and thus energy policies are reviewed to overcome challenges to accelerating deployment of black mc-Si PERC across the PV industry.
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Kremenak JW, Arendse CJ, Cummings FR, Chen Y, Miceli PF. Insight on the silver catalyst distribution during silicon nanowire array formation: an X-ray reflectivity study. NANOSCALE 2017; 9:19073-19085. [PMID: 29120464 DOI: 10.1039/c7nr05676a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Although metal-catalysts are commonly used to create nanoscale materials at surfaces, little is quantitatively known or understood about the depth distribution profile of the catalyst during the growth process. Using X-ray reflectivity, we report the first quantitative investigation, with nanoscale resolution, of the Ag metal-catalyst depth distribution profile during metal-assisted chemical etch (MACE) growth of Si nanowire (SiNW) arrays on Si(100). Given the very low optical reflectivity of these nanowire arrays, specular reflection from these materials in the X-ray region is extremely challenging to measure because it probes interfaces on the nanoscale. Nevertheless, we demonstrate that with suitable investigation, X-ray specular reflection can be measured and utilized to obtain unique structural information about the composition profile of both Ag and Si. The measurements, which also include X-ray diffraction and complementary electron microscopy, reveal that the Ag nanoparticles distribute along the length of the nanowires upon etching with a Ag density that increases towards the etch front. The Ag nanoparticles coarsen with etch time, indicating a high mobility of Ag ions even though we also find that the Ag does not migrate from the SiNW region into the etch bath during etching. The Ag density gradient and the Ag mobility suggest the existence of a strong chemical force that attracts Ag towards the etch front. These results provide unique and important new insight into the growth process for creating SiNWs from wet chemical etching using metal-catalysts.
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Affiliation(s)
- Jesse W Kremenak
- Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211, USA.
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Wang Y, Liu Y, Yang L, Chen W, Du X, Kuznetsov A. Micro-structured inverted pyramid texturization of Si inspired by self-assembled Cu nanoparticles. NANOSCALE 2017; 9:907-914. [PMID: 28000825 DOI: 10.1039/c6nr08126f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A superior micron-sized inverted pyramid structure has been successfully achieved by one-step copper nanoparticles assisted chemical etching in Si/Cu(NO3)2/HF/H2O2 solution for light trapping in silicon solar cells. The detailed mechanisms of such a novel method have been systematically demonstrated. The charge transfer during the reaction has been revealed by the simplified energy band diagram of the system as well. In order to form micro-structured inverted pyramids, the generation and dissolution of Cu nanoparticles should keep in balance during the reaction, which depends on the concentration of the etchant, the doping type and the doping level of the silicon substrate. With the investigation of the intrinsic properties of the silicon substrate, the etching rate is found out as a combined result of the electron concentration and the defect density of the substrate, as well as the potential barrier on the interface of Si/Cu nanoparticles. Furthermore, the anisotropic nature of Cu assisted chemical etching has also been investigated.
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Affiliation(s)
- Yan Wang
- Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China. and Department of Physics, University of Oslo, Oslo, 0316, Norway.
| | - Yaoping Liu
- Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
| | - Lixia Yang
- Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
| | - Wei Chen
- Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
| | - Xiaolong Du
- Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
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Toor F, Miller JB, Davidson LM, Nichols L, Duan W, Jura MP, Yim J, Forziati J, Black MR. Nanostructured silicon via metal assisted catalyzed etch (MACE): chemistry fundamentals and pattern engineering. NANOTECHNOLOGY 2016; 27:412003. [PMID: 27609489 DOI: 10.1088/0957-4484/27/41/412003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
There are a range of different methods to generate a nanostructured surface on silicon (Si) but the most cost effective and optically interesting is the metal assisted wet chemical etching (MACE) (Koynov et al 2006 Appl. Phys. Lett. 88 203107). MACE of Si is a controllable, room-temperature wet-chemical technique that uses a thin layer of metal to etch the surface of Si, leaving behind various nano- and micro-scale surface features or 'black silicon'. MACE-fabricated nanowires (NWs) provide improved antireflection and light trapping functionality (Toor et al 2016 Nanoscale 8 15448-66) compared with the traditional 'iso-texturing' (Campbell and Green 1987 J. Appl. Phys. 62 243-9). The resulting lower reflection and improved light trapping can lead to higher short circuit currents in NW solar cells (Toor et al 2011 Appl. Phys. Lett. 99 103501). In addition, NW cells can have higher fill factors and voltages than traditionally processed cells, thus leading to increased solar cell efficiencies (Cabrera et al 2013 IEEE J. Photovolt. 3 102-7). MACE NW processing also has synergy with next generation Si solar cell designs, such as thin epitaxial-Si and passivated emitter rear contact (Toor et al 2016 Nanoscale 8 15448-66). While several companies have begun manufacturing black Si, and many more are researching these techniques, much of the work has not been published in traditional journals and is publicly available only through conference proceedings and patent publications, which makes learning the field challenging. There have been three specialized review articles published recently on certain aspects of MACE or black Si, but do not present a full review that would benefit the industry (Liu et al 2014 Energy Environ. Sci. 7 3223-63; Yusufoglu et al 2015 IEEE J. Photovolt. 5 320-8; Huang et al 2011 Adv. Mater. 23 285-308). In this feature article, we review the chemistry of MACE and explore how changing parameters in the wet etch process effects the resulting texture on the Si surface. Then we review efforts to increase the uniformity and reproducibility of the MACE process, which is critical for commercializing the black Si technology.
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Affiliation(s)
- Fatima Toor
- Electrical and Computer Engineering Department, University of Iowa, Iowa City, IA 52242, USA. Physics and Astronomy Department, University of Iowa, Iowa City, IA 52242, USA. Optical Science and Technology Center, University of Iowa, Iowa City, IA 52242, USA. University of Iowa Informatics Initiative, University of Iowa, Iowa City, IA 52242, USA
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