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Kumar M, Kim D, Seo H. Flexo-Pyrophotronic Effect Modulated Giant Near Infrared Photoresponse from VO 2 -Based Heterojunction for Optical Communication. SMALL METHODS 2024; 8:e2300425. [PMID: 37423964 DOI: 10.1002/smtd.202300425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/12/2023] [Indexed: 07/11/2023]
Abstract
The flexoelectric phenomenon, which occurs when materials undergo mechanical deformation and cause strain gradients and a related spontaneous electric polarization field, can result in wide variety of energy- and cost-saving mechano-opto-electronics, such as night vision, communication, and security. However, accurate sensing of weak intensities under self-powered conditions with stable photocurrent and rapid temporal response remains essential despite the challenges related to having suitable band alignment and high junction quality. Taking use of the flexoelectric phenomena, it is shown that a centrosymmetric VO2 -based heterojunction exhibits a self-powered (i.e., 0 V), infrared (λ = 940 nm) photoresponse. Specifically, the device shows giant current modulation (103 %), good responsivity of >2.4 mA W-1 , reasonable specific detectivity of ≈1010 Jones, and a fast response speed of 0.5 ms, even at the nanoscale modulation. Through manipulation of the applied inhomogeneous force, the sensitivity of the infrared response is enhanced (> 640%). Ultrafast night optical communication like Morse code distress (SOS) signal sensing and high-performing obstacle sensors with potential impact alarms are created as proof-of-concept applications. These findings validate the potential of emerging mechanoelectrical coupling for a wide variety of novel applications, including mechanoptical switches, photovoltaics, sensors, and autonomous vehicles, which require tunable optoelectronic performance.
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Affiliation(s)
- Mohit Kumar
- Department of Energy Systems Research, Ajou University, Suwon, 16499, Republic of Korea
- Department of Materials Science and Engineering, Ajou University, Suwon, 16499, Republic of Korea
| | - Dukhwan Kim
- Department of Energy Systems Research, Ajou University, Suwon, 16499, Republic of Korea
| | - Hyungtak Seo
- Department of Energy Systems Research, Ajou University, Suwon, 16499, Republic of Korea
- Department of Materials Science and Engineering, Ajou University, Suwon, 16499, Republic of Korea
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Kumar M, Lim S, Kim J, Seo H. Picoampere Dark Current and Electro-Opto-Coupled Sub-to-Super-linear Response from Mott-Transition Enabled Infrared Photodetector for Near-Sensor Vision Processing. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2210907. [PMID: 36740630 DOI: 10.1002/adma.202210907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 02/01/2023] [Indexed: 05/05/2023]
Abstract
Light-intensity selective superlinear photodetectors with ultralow dark current can provide an essential breakthrough for the development of high-performing near-sensor vision processing. However, the development of near-sensor vision processing is not only conceptually important for device operation (given that sensors naturally exhibit linear/sublinear responses), but also essential to get rid of the massive amount of data generated during object sensing and classification with noisy inputs. Therefore, achieving the giant superlinear photoresponse while maintaining the picoampere leakage current, irrespective of the measurement bias, is one of the most challenging tasks. Here, Mott material (vanadium dioxide) and silicon-based integrated infrared photodetectors are developed that show giant superlinear photoresponse (exponent >18) and ultralow dark current of 4.46 pA. Specifically, the device demonstrates an electro-opto-coupled insulator-to-metal transition, which leads to outstanding photocurrent on/off ratio (>106 ), a high responsivity (>1 mA W-1 ), and excellent detectivity (>1012 Jones), while maintaining response speed (τr = 6 µs and τf = 10 µs). Further, intensity-selective near-sensor processing is demonstrated and night vision pattern reorganization even with noisy inputs is exhibited. This research will pave the way for the creation of high-performance photodetectors with potential uses, such as in night vision, pattern recognition, and neuromorphic processing.
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Affiliation(s)
- Mohit Kumar
- Department of Energy Systems Research, Ajou University, Suwon, 16499, Republic of Korea
- Department of Materials Science and Engineering, Ajou University, Suwon, 16499, Republic of Korea
| | - Seokwon Lim
- Department of Energy Systems Research, Ajou University, Suwon, 16499, Republic of Korea
| | - Jisu Kim
- Department of Energy Systems Research, Ajou University, Suwon, 16499, Republic of Korea
| | - Hyungtak Seo
- Department of Energy Systems Research, Ajou University, Suwon, 16499, Republic of Korea
- Department of Materials Science and Engineering, Ajou University, Suwon, 16499, Republic of Korea
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Kumar M, Seo H. Adaptive Memory and In Materia Reinforcement Learning Enabled by Flexoelectric-like Response from Ultrathin HfO 2. ACS APPLIED MATERIALS & INTERFACES 2022; 14:54876-54884. [PMID: 36450008 DOI: 10.1021/acsami.2c19148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Reinforcement learning (RL) is a mathematical framework of neural learning by trial and error that revolutionized the field of artificial intelligence. However, until now, RL has been implemented in algorithms with the compatibly of traditional complementary metal-oxide-semiconductor-based von Neumann digital platforms, which thus limits performance in terms of latency, fault tolerance, and robustness. Here, we demonstrate that nanocolumnar (∼12 nm) HfO2 structures can be used as building blocks to conduct the RL within the material by combining its stress-adjustable charge transport and memory functions. Specifically, HfO2 nanostructures grown by the sputtering method exhibit self-assembled vertical nanocolumnar structures that generate voltage depending on the impact of stress under self-biased conditions. The observed results are attributed to the flexoelectric-like response of HfO2. Further, multilevel current (>10-3 A) modulation with touch and controlled suspension (∼10-12 A) with a short electric pulse (100 ms) were demonstrated, yielding a proof-of-concept memory with an on/off ratio greater than 109. Utilizing multipattern dynamic memory and tactile sensing, RL was implemented to successfully solve a maze game using an array of 6 × 4. This work could pave the way to do RL within materials for a variety of applications such as memory storage, neuromorphic sensors, smart robots, and human-machine interaction systems.
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Affiliation(s)
- Mohit Kumar
- Department of Energy Systems Research, Ajou University, Suwon16499, Republic of Korea
- Department of Materials Science and Engineering, Ajou University, Suwon16499, Republic of Korea
| | - Hyungtak Seo
- Department of Energy Systems Research, Ajou University, Suwon16499, Republic of Korea
- Department of Materials Science and Engineering, Ajou University, Suwon16499, Republic of Korea
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Feng P, Zhao S, Dang C, He S, Li M, Zhao L, Gao L. Improving the photoresponse performance of monolayer MoS 2photodetector via local flexoelectric effect. NANOTECHNOLOGY 2022; 33:255204. [PMID: 35287121 DOI: 10.1088/1361-6528/ac5da1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 03/14/2022] [Indexed: 06/14/2023]
Abstract
Strain engineering is an effective means of modulating the optical and electrical properties of two-dimensional materials. The flexoelectric effect caused by inhomogeneous strain exists in most dielectric materials, which breaks the limit of the materials' non-centrosymmetric structure for piezoelectric effect. However, there is a lack of understanding of the impact on optoelectronic behaviour of monolayer MoS2photodetector via local flexoelectric effect triggered by biaxial strain. In this paper, we develop a probe tip (Pt)-MoS2-Au asymmetric Schottky barrier photodetector based on conductive atomic force microscopy to investigate the impact of flexoelectric effect on the photoresponse performance. Consequently, when the probe force increases from 24 nN to 720 nN, the photocurrent, responsivity and detectivity increase 28.5 times, 29.6 times and 5.3 times at forward bias under 365 nm light illumination, respectively. These results indicate that local flexoelectric effect plays a critical role to improve the photoresponse performance of photodetector. Our approach suggests a new route to improve the performance of photodetectors by introducing local flexoelectric polarization field, offering the potential for the application of strain modulated photoelectric devices.
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Affiliation(s)
- Pu Feng
- Institute of Electronic Materials and Technology, School of Material Science and Engineering Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Sixiang Zhao
- Institute of Electronic Materials and Technology, School of Material Science and Engineering Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Congcong Dang
- Institute of Electronic Materials and Technology, School of Material Science and Engineering Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Sixian He
- Institute of Electronic Materials and Technology, School of Material Science and Engineering Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Ming Li
- Institute of Electronic Materials and Technology, School of Material Science and Engineering Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Liancheng Zhao
- Institute of Electronic Materials and Technology, School of Material Science and Engineering Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Liming Gao
- Institute of Electronic Materials and Technology, School of Material Science and Engineering Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
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Shih Y, Li W, Shen J, Chu S, Uen W, Lee H, Lin G, Chen Y, Tu W. Low‐Power Photodetectors Based on PVA Modified Reduced Graphene Oxide Hybrid Solutions. Macromol Rapid Commun 2022; 43:e2100854. [DOI: 10.1002/marc.202100854] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 02/23/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Yi‐Shan Shih
- Department of Electrical Engineering National Cheng Kung University No.1, University Road Tainan City 701 Taiwan
| | - Wei‐Chen Li
- Department of Electronic Engineering Chung Yuan Christian University No. 200, Chung‐Pei Road, Chungli District Taoyuan City 320 Taiwan
| | - Jun‐Hao Shen
- Department of Electrical Engineering National Cheng Kung University No.1, University Road Tainan City 701 Taiwan
| | - Shao‐Yu Chu
- Department of Electrical Engineering National Cheng Kung University No.1, University Road Tainan City 701 Taiwan
| | - Wu‐Yih Uen
- Department of Electronic Engineering Chung Yuan Christian University No. 200, Chung‐Pei Road, Chungli District Taoyuan City 320 Taiwan
| | - Hsin‐Ying Lee
- Department of Electrical Engineering National Cheng Kung University No.1, University Road Tainan City 701 Taiwan
| | - Gong‐Ru Lin
- Department of Electrical Engineering National Taiwan University No. 1, Sec. 4, Roosevelt Rd. Taipei 10617 Taiwan
| | - Yu‐Cheng Chen
- School of Electrical and Electronic Engineering Nanyang Technological University 50 Nanyang Avenue Singapore 639798 Singapore
| | - Wei‐Chen Tu
- Department of Electrical Engineering National Cheng Kung University No.1, University Road Tainan City 701 Taiwan
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