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Huang X, Chen C, Sun F, Chen X, Xu W, Li L. Enhancing the Carrier Mobility and Bias Stability in Metal-Oxide Thin Film Transistors with Bilayer InSnO/a-InGaZnO Heterojunction Structure. Micromachines (Basel) 2024; 15:512. [PMID: 38675323 PMCID: PMC11051983 DOI: 10.3390/mi15040512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 04/01/2024] [Accepted: 04/09/2024] [Indexed: 04/28/2024]
Abstract
In this study, the electrical performance and bias stability of InSnO/a-InGaZnO (ITO/a-IGZO) heterojunction thin-film transistors (TFTs) are investigated. Compared to a-IGZO TFTs, the mobility (µFE) and bias stability of ITO/a-IGZO heterojunction TFTs are enhanced. The band alignment of the ITO/a-IGZO heterojunction is analyzed by using X-ray photoelectron spectroscopy (XPS). A conduction band offset (∆EC) of 0.5 eV is observed in the ITO/a-IGZO heterojunction, resulting in electron accumulation in the formed potential well. Meanwhile, the ∆EC of the ITO/a-IGZO heterojunction can be modulated by nitrogen doping ITO (ITON), which can affect the carrier confinement and transport properties at the ITO/a-IGZO heterojunction interface. Moreover, the carrier concentration distribution at the ITO/a-IGZO heterointerface is extracted by means of TCAD silvaco 2018 simulation, which is beneficial for enhancing the electrical performance of ITO/a-IGZO heterojunction TFTs.
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Affiliation(s)
- Xiaoming Huang
- College of Integrated Circuit Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China; (C.C.); (F.S.); (X.C.)
| | - Chen Chen
- College of Integrated Circuit Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China; (C.C.); (F.S.); (X.C.)
| | - Fei Sun
- College of Integrated Circuit Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China; (C.C.); (F.S.); (X.C.)
| | - Xinlei Chen
- College of Integrated Circuit Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China; (C.C.); (F.S.); (X.C.)
| | - Weizong Xu
- National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China;
| | - Lin Li
- Key Laboratory of Laser Technology and Optoelectronic Functional Materials of Hainan Province, College of Physics and Electronic Engineering, Hainan Normal University, Haikou 571158, China;
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Park HK, Cho Y, Kim K, Jeong I, Gwak J, Yun JH, Jo W. Tailored Band Structure of Cu(In,Ga)Se 2 Thin-Film Heterojunction Solar Cells: Depth Profiling of Defects and the Work Function. ACS Appl Mater Interfaces 2022; 14:34697-34705. [PMID: 35856522 DOI: 10.1021/acsami.2c07166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
An efficient carrier transport is essential for enhancing the performance of thin-film solar cells, in particular Cu(In,Ga)Se2 (CIGS) solar cells, because of their great sensitivities to not only the interface but also the film bulk. Conventional methods to investigate the outcoming carriers and their transport properties measure the current and voltage either under illumination or dark conditions. However, the evaluation of current and voltage changes along the cross-section of the devices presents several limitations. To mitigate this shortcoming, we prepared gently etched devices and analyzed their properties using micro-Raman scattering spectroscopy, Kelvin probe force microscopy, and photoluminescence measurements. The atomic distributions and microstructures of the devices were investigated, and the defect densities in the device bulk were determined via admittance spectroscopy. The effects of Ga grading on the charge transport at the CIGS-CdS interface were categorized into various types of band offsets, which were directly confirmed by our experiments. The results indicated that reducing open-circuit voltage loss is crucial for obtaining a higher power conversion efficiency. Although the large Ga grading in the CIGS absorber induced higher defect levels, it effectuated a smaller open-circuit voltage loss because of carrier transport enhancement at the absorber-buffer interface, resulting from the optimized conduction band offsets.
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Affiliation(s)
- Ha Kyung Park
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Yunae Cho
- New and Renewable Energy Research Center, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Kihwan Kim
- Photovoltaic Laboratory, Korea Institute of Energy Research (KIER), Daejeon 34129, Republic of Korea
| | - Inyoung Jeong
- Photovoltaic Laboratory, Korea Institute of Energy Research (KIER), Daejeon 34129, Republic of Korea
| | - Jihye Gwak
- Photovoltaic Laboratory, Korea Institute of Energy Research (KIER), Daejeon 34129, Republic of Korea
| | - Jae Ho Yun
- Department of Energy Engineering, Korea Institute of Energy Technology, Naju 58330, Republic of Korea
| | - William Jo
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
- New and Renewable Energy Research Center, Ewha Womans University, Seoul 03760, Republic of Korea
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Yokoyama T, Nishitani Y, Miyamoto Y, Kusumoto S, Uchida R, Matsui T, Kawano K, Sekiguchi T, Kaneko Y. Improving the Open-Circuit Voltage of Sn-Based Perovskite Solar Cells by Band Alignment at the Electron Transport Layer/Perovskite Layer Interface. ACS Appl Mater Interfaces 2020; 12:27131-27139. [PMID: 32427458 DOI: 10.1021/acsami.0c04676] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Organic-inorganic lead halide perovskites are promising materials for realization of low-cost and high-efficiency solar cells. Because of the toxicity of lead, Sn-based perovskite materials have been developed as alternatives to enable fabrication of Pb-free perovskite solar cells. However, the solar cell performance of Sn-based perovskite solar cells (Sn-PSCs) remains poor because of their large open-circuit voltage (VOC) loss. Sn-based perovskite materials have lower electron affinities than Pb-based perovskite materials, which result in larger conduction band offset (CBO) values at the interface between the Sn-based perovskite and a conventional electron transport layer (ETL) material such as TiO2. Herein, the relationship between the VOC and the CBO in these devices was studied to improve the solar cell performances of Sn-PSCs. It was found that the band offset at the ETL/perovskite layer interface affects the VOC of the Sn-PSCs significantly but does not affect that of the Pb-PSCs because the Sn-based perovskite material is a p-type semiconductor, unlike the Pb-based perovskite. It was also found that Nb2O5 has the CBO that is closest to zero for Sn-based perovskite materials, and the VOC values of Sn-PSCs that use Nb2O5 as their ETL are higher than those of Sn-PSCs using TiO2 or SnO2 ETLs. This study indicates that control of the energy alignment at the ETL/perovskite layer interface is an important factor in improving the VOC values of Sn-PSCs.
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Affiliation(s)
- Tomoyasu Yokoyama
- Technology Innovation Division, Panasonic Corporation, 3-1-1 Yagumo-nakamachi, Moriguchi City, Osaka 570-8501, Japan
| | - Yu Nishitani
- Technology Innovation Division, Panasonic Corporation, 3-1-1 Yagumo-nakamachi, Moriguchi City, Osaka 570-8501, Japan
| | - Yumi Miyamoto
- Technology Innovation Division, Panasonic Corporation, 3-1-1 Yagumo-nakamachi, Moriguchi City, Osaka 570-8501, Japan
| | - Shohei Kusumoto
- Technology Innovation Division, Panasonic Corporation, 3-1-1 Yagumo-nakamachi, Moriguchi City, Osaka 570-8501, Japan
| | - Ryusuke Uchida
- Technology Innovation Division, Panasonic Corporation, 3-1-1 Yagumo-nakamachi, Moriguchi City, Osaka 570-8501, Japan
| | - Taisuke Matsui
- Technology Innovation Division, Panasonic Corporation, 3-1-1 Yagumo-nakamachi, Moriguchi City, Osaka 570-8501, Japan
| | - Kenji Kawano
- Technology Innovation Division, Panasonic Corporation, 3-1-1 Yagumo-nakamachi, Moriguchi City, Osaka 570-8501, Japan
| | - Takashi Sekiguchi
- Technology Innovation Division, Panasonic Corporation, 3-1-1 Yagumo-nakamachi, Moriguchi City, Osaka 570-8501, Japan
| | - Yukihiro Kaneko
- Technology Innovation Division, Panasonic Corporation, 3-1-1 Yagumo-nakamachi, Moriguchi City, Osaka 570-8501, Japan
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Quah HJ, Cheong KY. Effects of post-deposition annealing ambient on band alignment of RF magnetron-sputtered Y2O3 film on gallium nitride. Nanoscale Res Lett 2013; 8:53. [PMID: 23360596 PMCID: PMC3598984 DOI: 10.1186/1556-276x-8-53] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2012] [Accepted: 01/20/2013] [Indexed: 06/01/2023]
Abstract
The effects of different post-deposition annealing ambients (oxygen, argon, forming gas (95% N2 + 5% H2), and nitrogen) on radio frequency magnetron-sputtered yttrium oxide (Y2O3) films on n-type gallium nitride (GaN) substrate were studied in this work. X-ray photoelectron spectroscopy was utilized to extract the bandgap of Y2O3 and interfacial layer as well as establishing the energy band alignment of Y2O3/interfacial layer/GaN structure. Three different structures of energy band alignment were obtained, and the change of band alignment influenced leakage current density-electrical breakdown field characteristics of the samples subjected to different post-deposition annealing ambients. Of these investigated samples, ability of the sample annealed in O2 ambient to withstand the highest electric breakdown field (approximately 6.6 MV/cm) at 10-6 A/cm2 was related to the largest conduction band offset of interfacial layer/GaN (3.77 eV) and barrier height (3.72 eV).
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Affiliation(s)
- Hock Jin Quah
- Energy Efficient & Sustainable Semiconductor Research Group, School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Engineering Campus, Nibong Tebal, Seberang Perai Selatan, Penang, 14300, Malaysia
| | - Kuan Yew Cheong
- Energy Efficient & Sustainable Semiconductor Research Group, School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Engineering Campus, Nibong Tebal, Seberang Perai Selatan, Penang, 14300, Malaysia
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