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Li T, Lu Y, Chen Z. Heteroepitaxy Growth and Characterization of High-Quality AlN Films for Far-Ultraviolet Photodetection. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:4169. [PMID: 36500790 PMCID: PMC9737869 DOI: 10.3390/nano12234169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 11/09/2022] [Accepted: 11/18/2022] [Indexed: 06/17/2023]
Abstract
The ultra-wide bandgap (~6.2 eV), thermal stability and radiation tolerance of AlN make it an ideal choice for preparation of high-performance far-ultraviolet photodetectors (FUV PDs). However, the challenge of epitaxial crack-free AlN single-crystalline films (SCFs) on GaN templates with low defect density has limited its practical applications in vertical devices. Here, a novel preparation strategy of high-quality AlN films was proposed via the metal organic chemical vapor deposition (MOCVD) technique. Cross-sectional transmission electron microscopy (TEM) studies clearly indicate that sharp, crack-free AlN films in single-crystal configurations were achieved. We also constructed a p-graphene/i-AlN/n-GaN photovoltaic FUV PD with excellent spectral selectivity for the FUV/UV-C rejection ratio of >103, a sharp cutoff edge at 206 nm and a high responsivity of 25 mA/W. This work provides an important reference for device design of AlN materials for high-performance FUV PDs.
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Affiliation(s)
- Titao Li
- Jinjiang Joint Institute of Microelectronics, College of Physics and Information Engineering, Fuzhou University, Fuzhou 350108, China
| | - Yaoping Lu
- Jinjiang Joint Institute of Microelectronics, College of Physics and Information Engineering, Fuzhou University, Fuzhou 350108, China
| | - Zuxin Chen
- School of Semiconductor Science and Technology, South China Normal University, Foshan 528225, China
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2
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Cheng L, Zheng W, Zhu Y, Huang F, Wang H, Ouyang X. Anomalous Blue Shift of Exciton Luminescence in Diamond. NANO LETTERS 2022; 22:1604-1608. [PMID: 35129990 DOI: 10.1021/acs.nanolett.1c04519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Generally speaking, for a semiconductor, the temperature dependence of excitonic emission corresponds to that of its band gap. However, an anomalous behavior is exhibited by the excitonic luminescence of diamond where as the temperature increases (from 10 to 300 K), its indirect exciton luminescence peak displays a spectral-distinguishable blue shift, whereas the indirect band-gap absorption shows a weak red shift. According to experimental high-resolution deep-ultraviolet spectra and theoretical analysis, the weak red shift of its indirect band gap is ascribed to its large Debye temperature (ΘD ≈ 2220 K), which makes the lattice constant change comparatively little in a large temperature range, so the change of its band gap is relatively small; in this case, as the temperature rises, the thermal population of valence-band holes that moves to a high-energy state far away from the Fermi surface contributes to the macroscopic blue shift of its excitonic emission.
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Affiliation(s)
- Lu Cheng
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Wei Zheng
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Yanming Zhu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Feng Huang
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Haikuo Wang
- College of Energy Engineering, Zhejiang University, Hanzhou 310000, China
| | - Xiaoping Ouyang
- School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, China
- State Key Laboratory of Intense Pulsed Radiation Simulation and Effect and Radiation Detection Research Center, Northwest Institute of Nuclear Technology, 710024 Xi'an, China
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Li T, Jia L, Zheng W, Huang F. Fermi-Surface Modulation of Graphene Synergistically Enhances the Open-Circuit Voltage and Quantum Efficiency of Photovoltaic Solar-Blind Ultraviolet Detectors. J Phys Chem Lett 2021; 12:11106-11113. [PMID: 34752104 DOI: 10.1021/acs.jpclett.1c03279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Increasing the open-circuit voltage (VOC) is of a great significance to achieve high photoelectric conversion efficiency in photovoltaic applications. Here, we present a simple NO2 doping strategy that can significantly modulate the VOC of graphene-based solar-blind ultraviolet photodetectors from 0.96 to 1.84 V. The intriguing result can be demonstrated by the fact that NO2 doping lowers the Fermi surface of graphene and thus enhances quasi-Fermi level splitting of the whole device under illumination. The >103% increase of both external quantum efficiency and photoresponsivity compared to before doping is the result of a 0.88 V increase in the VOC. Our work sheds light on the forming mechanism of VOC in graphene-based photovoltaic detectors and further suggests alternative pathways to enhance the VOC of photovoltaic devices with high efficiency.
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Affiliation(s)
- Titao Li
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Lemin Jia
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Wei Zheng
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Feng Huang
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
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Li T, Zheng W, Zhu S, Wang F, Zhu Y, Jia L, Lin Z, Huang F. High-Pressure O 2 Annealing Enhances the Crystallinity of Ultrawide-Band-Gap Sesquioxides Combined with Graphene for Vacuum-Ultraviolet Photovoltaic Detection. ACS APPLIED MATERIALS & INTERFACES 2021; 13:16660-16668. [PMID: 33787197 DOI: 10.1021/acsami.1c00429] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
(AlxGa1-x)2O3 is emerging as a promising wide-band-gap sesquioxide for vacuum-ultraviolet (VUV, 10-200 nm) photodetectors and high-power field-effect transistors. However, how the key parameters such as the band gap and crystalline phase of the (AlxGa1-x)2O3-based device vary with stoichiometry has not been explicitly defined, which is due to the unclear underlying mechanism of the Al local coordination environment. In this work, a high-pressure O2 (20 atm) annealing (HPOA) strategy that can significantly improve the crystallinity of β-(AlxGa1-x)2O3 and achieve a tunable optical band gap was proposed, facilitating the revelation of the local structure of Al3+ varying with Al content and the kinetic mechanism of Al3+ diffusion. By combining the as-HPOA-treated single-crystalline β-(Al0.69Ga0.31)2O3 films with p-type graphene (p-Gr), which serves as a transparent conductor, a VUV photovoltaic detector is fabricated, showing an improved photovoltage (0.80 V) and fast temporal response (2.1 μs). All of these findings provide a rewarding and important strategy for enhancing the band-gap tunability of sesquioxides, as well as the flexibility of zero-power-consumption photodetectors.
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Affiliation(s)
- Titao Li
- School of Materials, Sun Yat-sen University, Guangzhou, Guangdong 510275, China
| | - Wei Zheng
- School of Materials, Sun Yat-sen University, Guangzhou, Guangdong 510275, China
| | - Siqi Zhu
- School of Materials, Sun Yat-sen University, Guangzhou, Guangdong 510275, China
| | - Fei Wang
- School of Materials, Sun Yat-sen University, Guangzhou, Guangdong 510275, China
| | - Yanming Zhu
- School of Materials, Sun Yat-sen University, Guangzhou, Guangdong 510275, China
| | - Lemin Jia
- School of Materials, Sun Yat-sen University, Guangzhou, Guangdong 510275, China
| | - Zeguo Lin
- School of Materials, Sun Yat-sen University, Guangzhou, Guangdong 510275, China
| | - Feng Huang
- School of Materials, Sun Yat-sen University, Guangzhou, Guangdong 510275, China
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Ding Y, Zheng W, Lu X, Liang Y, Zhu Y, Jin M, Huang F. Raman Tensor of Layered SnS 2. J Phys Chem Lett 2020; 11:10094-10099. [PMID: 33186027 DOI: 10.1021/acs.jpclett.0c03024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Recently, tin disulfide (SnS2) has become a hot research focus in various fields due to its advantages of a high transistor switching ratio, an adjustable band gap in visible light range, excellent Li storage performance, sensitive gas recognition, and efficient photocatalytic capability. However, at present, studies of its basic structure mostly stay on the regulation related to the number of layers. To maximize the value of SnS2 in the application design, this paper analyzes the angle-resolved polarized Raman spectra of SnS2 crystals grown under high-temperature sealing systems. Under the parallel scattering configuration test of both the sample basal plane and the cross plane, we observed that how the Raman scattering intensity of the two test planes varies with the polarization angle is different. Combining this experimental result with theory support allows us to reach a conclusion that the differential polarizability of the phonon vibration mode along the z-axis of the cross plane of SnS2 is proven to be the strongest. This finding is expected to provide favorable support for the application of structural regulation of SnS2 and work as a reference for studying other van der Waals layered materials with greater potential.
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Affiliation(s)
- Ying Ding
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Wei Zheng
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Xuefang Lu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Yali Liang
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Yanming Zhu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Mingge Jin
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Feng Huang
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
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Cheng L, Zheng W, Jia L, Huang F. Quasiphonon polaritons. Heliyon 2020; 6:e05277. [PMID: 33134580 PMCID: PMC7586075 DOI: 10.1016/j.heliyon.2020.e05277] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 09/21/2020] [Accepted: 10/12/2020] [Indexed: 11/29/2022] Open
Abstract
Mid-infrared reflection spectra of c- and m-plane bulk AlN show a reststrahlen band related to the formation of phonon polaritons. However, it is worth noting that there are additional hump- and spike-shaped peaks in the spectra, which cannot be explained by the phonon-polaritons model applicable to optically isotropic crystals. Here, considering the existence of quasiphonons in wurtzite crystals, we suppose that the extra peaks result from the generation of quasiphonon polaritons (QPPs) induced by the coupling between photon and quasi-transverse optical phonon. On the basis of this point, a QPPs model applicable to optically anisotropic wurtzite crystals is developed, which successfully explains the reststrahlen band of bulk AlN. Besides, on the ground of our model, a series of reststrahlen band of bulk AlN under various configurations is also predicted and presented.
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Affiliation(s)
- Lu Cheng
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Wei Zheng
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Lemin Jia
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Feng Huang
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
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Lin R, Zheng W, Chen L, Zhu Y, Xu M, Ouyang X, Huang F. X-ray radiation excited ultralong (>20,000 seconds) intrinsic phosphorescence in aluminum nitride single-crystal scintillators. Nat Commun 2020; 11:4351. [PMID: 32859949 PMCID: PMC7455697 DOI: 10.1038/s41467-020-18221-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Accepted: 08/05/2020] [Indexed: 11/09/2022] Open
Abstract
Phosphorescence is a fascinating photoelectronic phenomenon usually observed in rare-earth-doped inorganic crystals and organic molecular crystals, owning great potential in optical information storage, color display and biological dosimetry. Here, we present an ultralong intrinsic phosphorescence (>20,000 seconds) in AlN single-crystal scintillator through X-ray excitation. We suggest that the long afterglow emission originates from the intra-band transition related to native nitrogen vacancy. Some excited states formed by absorbing X-ray photons cannot satisfy the parity difference between initial and final states required by transition selection rule, so they cannot return to the ground state directly through radiation transitions but through several phonon-assisted intra-band transitions slowly. During this process, a long-term broad-spectra phosphorescence emission is formed. Investigating the X-ray excited phosphorescence emission in the AlN is of great significance to understanding the mechanism of phosphorescence in inorganic materials, and to realizing the practical applications in high-energy ray dosimetry.
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Affiliation(s)
- Richeng Lin
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, 510275, Guangzhou, China
| | - Wei Zheng
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, 510275, Guangzhou, China.
| | - Liang Chen
- State Key Laboratory of Intense Pulsed Radiation Simulation and Effect and Radiation Detection Research Center, Northwest Institute of Nuclear Technology, 710024, Xi'an, China
| | - Yanming Zhu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, 510275, Guangzhou, China
| | - MengXuan Xu
- School of Nuclear Science and Technology, Xi'an Jiaotong University, 710049, Xi'an, China
| | - Xiaoping Ouyang
- State Key Laboratory of Intense Pulsed Radiation Simulation and Effect and Radiation Detection Research Center, Northwest Institute of Nuclear Technology, 710024, Xi'an, China
| | - Feng Huang
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, 510275, Guangzhou, China.
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Zheng W, Jia L, Huang F. Vacuum-Ultraviolet Photon Detections. iScience 2020; 23:101145. [PMID: 32446223 PMCID: PMC7243193 DOI: 10.1016/j.isci.2020.101145] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 04/28/2020] [Accepted: 05/04/2020] [Indexed: 11/17/2022] Open
Abstract
Vacuum-ultraviolet (VUV) photon detection technology is an effective means for the exploration in the field of space science (monitoring the formation and evolution of solar storms), high-energy physics (dark matter detection), large-scale scientific facility (VUV free electron lasers) and electronic industry (high-resolution lithography). The advancement of this technology mainly depends on the performance optimization of VUV photodetectors. In this review, we introduced the research progress on the typical VUV photodetectors based on scintillator, photomultiplier tube, semiconductor, and gas, with their unique advantages and optimal performance indicators in different applications summarized. In particular, during recent years, thanks to the advances in ultra-wide bandgap semiconductors, economical VUV photodetectors with low power consumption and small size have been encouragingly developed. Finally, we pointed out the remaining challenges for each type of VUV detector, with the aim of maximizing the performance in a variety of applications in the future.
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Affiliation(s)
- Wei Zheng
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China.
| | - Lemin Jia
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Feng Huang
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
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Zhu Y, Lin R, Zheng W, Ran J, Huang F. Near vacuum-ultraviolet aperiodic oscillation emission of AlN films. Sci Bull (Beijing) 2020; 65:827-831. [PMID: 36659201 DOI: 10.1016/j.scib.2020.02.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 01/28/2020] [Accepted: 02/14/2020] [Indexed: 01/21/2023]
Abstract
An accurate measurement of the refractive index is necessary for the optical design of both deep ultraviolet laser diodes and light-emitting diodes. Generally, the refractive indices along different crystallographic axes of anisotropic thin films are measured using variable angle spectroscopic ellipsometry. However, there are still some limitations concerning this method. Here we proposed a potential method to measure the band edge refractive index of wide bandgap semiconductor. An aperiodic oscillation emission phenomenon due to the Fabry-Perot effect was observed in the fluorescence spectrum of an AlN film with a thickness of 1500 nm. Based on the characteristics of the fluorescence spectrum and the definition of Fabry-Perot effect, we obtained the ordinary refractive index of the AlN thin film near the band edge directly. This refractive index measurement method is a supplement to the variable angle ellipsometry, and it is a more direct and effective method for transferred film and thinner samples to measure the fluorescence spectrum.
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Affiliation(s)
- Yanming Zhu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Richeng Lin
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
| | - Wei Zheng
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China.
| | - Junxue Ran
- Institute of Semiconductors, Chinese Academy of Science, Beijing 100083, China
| | - Feng Huang
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China
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Zhu Y, Zheng W, Ran J, Huang F. Deep-ultraviolet aperiodic-oscillation emission of AlGaN films. OPTICS LETTERS 2020; 45:1719-1721. [PMID: 32235982 DOI: 10.1364/ol.387256] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 02/18/2020] [Indexed: 06/11/2023]
Abstract
In this Letter, we describe an aperiodic-oscillation emission phenomenon originating from the Fabry-Perot effect in the deep-ultraviolet backscattering fluorescence spectrum of the $c$c-plane AlGaN film, which is related to the dispersion of its ordinary refractive index near the band edge. Based on this fluorescence spectrum, the ordinary refractive index of the AlGaN film near the band edge could be directly obtained. Certainly, by means of variable angle spectroscopic ellipsometry, the ordinary refractive index of the AlGaN film could be also achieved. Comparing the results obtained by both methods, we discovered that the refractive indices are quite similar, which suggests that the aperiodic-oscillation fluorescence spectrum is also a reliable approach to capture the refractive index of anisotropic optical films.
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