Article
Energy & Fuels
Aref Samadi, Alison Ciesla, Catherine Chan, Mattias Juhl
Summary: This study provides an alternative interpretation for the trapping-like behavior observed in materials with crystallographic defects. It suggests that the changes in the Fermi energy level at grain boundaries and the movement of majority carriers' quasi Fermi energy level during photoconductance measurement contribute to this behavior. Experimental results using cast-mono silicon wafers show variations in trapping signals and dark conductance that correlate with grain boundaries.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2022)
Article
Nuclear Science & Technology
Xiao-yu Zhang, Jun Zhong, Sheng-li Guo, Jun Zhao
Summary: Reasonable deformation and annealing treatment parameters lead to more incoherent Sigma 3 boundaries playing an important role in the optimization of GBE.
NUCLEAR MATERIALS AND ENERGY
(2021)
Article
Materials Science, Multidisciplinary
Cassidy M. Atkinson, Matthew C. Guziewski, Shawn P. Coleman, Sanjeev K. Nayak, S. Pamir Alpay
Summary: This study provides a detailed investigation on the formation energies of point defects and the stability of various dopants in bulk cubic silicon carbide and in grain boundaries, as well as the driving force of dopants towards grain boundaries. The results show different behaviors of dopants in grain boundaries, offering a chemical landscape for targeted materials development.
Article
Chemistry, Multidisciplinary
Pengcheng Jia, Liang Qin, Di Zhao, Yang Tang, Bo Song, Junhan Guo, Xiaomeng Li, Ling Li, Qiuhong Cui, Yufeng Hu, Zhidong Lou, Feng Teng, Yanbing Hou
Summary: The performance of perovskite solar cells is greatly influenced by the crystallization of the perovskite active layer, with neatly arranged crystal grains promoting less residual charge and improved device performance. The testing of residual charge at grain boundaries provides insight into carrier trap and detrap characteristics in photovoltaic devices.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Article
Energy & Fuels
Thomas Fiducia, Ashley Howkins, Ali Abbas, Budhika Mendis, Amit Munshi, Kurt Barth, Walajabad Sampath, John Walls
Summary: Cadmium telluride (CdTe) solar cells achieve high efficiencies through passivation of grain boundaries and grain interior defects. The use of selenium alloying in Cd(Se-x,Te1-x) material further improves the passivation effect, providing new possibilities for efficiency improvement and cost reduction in solar electricity.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2022)
Article
Chemistry, Multidisciplinary
Wenjie Li, Weimin Li, Guo Chen, Liyun Wu, Jun Zhang, Ming Chen, Guohua Zhong, Junyi Zhu, Ye Feng, Hao Zeng, Chunlei Yang
Summary: Conducting atomic force microscopy is used to investigate the mechanism behind the lower power conversion efficiency (PCE) of CZTS solar cells compared to CIGS solar cells. The difference in efficiency is attributed to the distinct band alignment at the grain boundaries and grain interior for the two materials. CZTS demonstrates type-I band alignment, leading to enhanced carrier recombination and decreased PCE.
Article
Crystallography
A. G. Chueshova, L. A. Pavlova, S. M. Peshcherova, A. Nepomnyashchikh
Summary: The orientation of grains and the special boundaries in multicrystalline silicon were studied, revealing the existence of certain special boundaries in this material, though not yet experimentally investigated.
CRYSTALLOGRAPHY REPORTS
(2021)
Article
Energy & Fuels
Utkarshaa Varshney, Moonyong Kim, Muhammad Umair Khan, Phillip Hamer, Catherine Chan, Malcolm Abbott, Bram Hoex
Summary: The study found that thinner silicon wafers are not naturally immune to Light and elevated-temperature-induced degradation (LeTID) and can still be affected at high temperatures. Thinner wafers do not necessarily exhibit faster recovery rates, and the higher hydrogen out-diffusion in thinner wafers during firing may lead to reduced degradation. The method used for thinning the wafers results in surface morphology variations, which could partly explain the correlation between wafer thickness and LeTID extent.
IEEE JOURNAL OF PHOTOVOLTAICS
(2021)
Article
Chemistry, Multidisciplinary
Lei Cao, Zhengji Zhou, Wenhui Zhou, Dongxing Kou, Yuena Meng, Shengjie Yuan, Yafang Qi, Litao Han, Qingwen Tian, Sixin Wu, Shengzhong (Frank) Liu
Summary: Grain boundaries (GBs) are the main cause of carrier loss in polycrystalline kesterite photovoltaic devices. This study introduces graphene as a passivator to improve the detrimental GBs. By adding graphene dispersion to the CZTSSe precursor solution, single-layer graphene is successfully incorporated into the GBs, transforming them into electrically benign regions. The efficiency of CZTSSe solar cells is significantly increased by using graphene additives.
Article
Energy & Fuels
Yuying Yao, Jing Zhang, Hang Su, Yong Li, Nan Li, Ting Nie, Lidan Liu, Xiaodong Ren, Ningyi Yuan, Jianning Ding, Shengzhong (Frank) Liu
Summary: Perovskite solar cells have high efficiency but low stability due to moisture permeation from grain boundaries and defects. A passivation agent called 3,4,5,6-tetrafluorophthalicacid (TFPA) is designed to improve both efficiency and stability. TFPA is found to distribute along grain boundaries, reducing film roughness and facilitating hole transporting. The device with TFPA modification shows outstanding efficiency and stability, with a champion efficiency of 23.70% and maintaining 90% of initial efficiency after 5200 hours.
Article
Optics
Peng You, Guanqi Tang, Jiupeng Cao, Dong Shen, Tsz-Wai Ng, Zafer Hawash, Naixiang Wang, Chun-Ki Liu, Wei Lu, Qidong Tai, Yabing Qi, Chun-Sing Lee, Feng Yan
Summary: A unique approach of modifying the edges of perovskite grain boundaries with high-mobility 2D materials can significantly enhance the performance of PSCs by conducting holes from the grain boundaries to the hole transport layers, forming hole channels in the devices. This cost-effective strategy presents a synergistic effect between the 2D flakes and perovskite grain boundaries for improving the photovoltaic performance of PSCs.
LIGHT-SCIENCE & APPLICATIONS
(2021)
Article
Energy & Fuels
Hooman Mehdizadeh-Rad, Farhad Mehdizadeh-Rad, Furong Zhu, Jai Singh
Summary: By developing a comprehensive mathematical model, the study simulated a perovskite solar cell and validated the model's accuracy. The impact of grain boundary diameter on the operating temperature was investigated, with a focus on the role of thermalization and thermal power at grain boundaries.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2021)
Article
Materials Science, Multidisciplinary
Wei Wan, Changxin Tang
Summary: In this atomistic study, the structure-property correlations of Si (001) small angle mixed grain boundaries (SAMGBs) were investigated. It was found that the energy trends of SAMGBs followed the revised Read-Shockley relationship, and the structural transitions were determined by the dislocation core radii. The proportion, topology and structural signatures of different SAMGB types were also examined.
Article
Materials Science, Multidisciplinary
Rita Maji, Eleonora Luppi, Nathalie Capron, Elena Degoli
Summary: This study investigates the effects of oxygen impurity segregation in Sigma 3{111} Si grain boundaries in the presence of strain and vacancies. The research provides insights into the complex mechanisms controlling oxygen atom segregation, offering a foundation for optimizing materials and improving solar cell efficiency.
Article
Energy & Fuels
Liang He, Yunfei Xu, Qi Lei, Shuai Yuan, Wei Mao, Hongzhi Luo, Xiaoping Li, Yitai Qian, Dongli Hu, Shengquan Gan
Summary: To improve the quality of multicrystalline silicon ingots and solar cells, a compact nucleation layer was designed. The results showed that the compact nucleation layer led to finer and more uniform nucleation grains, and reduced the number of grains with high defect density at the bottom of the ingot. Furthermore, the solar cell efficiency and electrical performance parameters were improved with the use of the compact nucleation layer.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2022)
Article
Physics, Applied
Ki-Hyun Jang, Takuya Saraya, Masaharu Kobayashi, Naomi Sawamoto, Atsushi Ogura, Toshiro Hiramoto
JAPANESE JOURNAL OF APPLIED PHYSICS
(2020)
Article
Physics, Applied
Michio Tajima, Shota Asahara, Yuta Satake, Atsushi Ogura
Summary: The study identified the spectral shape of the C08-band in silicon commonly observed after electron irradiation at room temperature, with a peak at 0.77 eV and long tails on both sides, sharing the same origin as the C-line. The long tails were explained by the superposition of phonon sidebands.
APPLIED PHYSICS EXPRESS
(2021)
Article
Physics, Applied
Riku Kobayashi, Toshihide Nabatame, Takashi Onaya, Akihiko Ohi, Naoki Ikeda, Takahiro Nagata, Kazuhito Tsukagoshi, Atsushi Ogura
Summary: The characteristics of thin-film transistors (TFTs) with amorphous In2O3 and carbon-doped In2O3 channels after post-metallization annealing (PMA) process were investigated. The In2O3 TFT changed behavior from metallic to switching after PMA at 200 degrees C, while the carbon-doped In2O3 TFT exhibited superior properties due to the reduction of excess oxygen vacancies.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Applied
Yosuke Shimura, Kako Iwamoto, Ryo Yokogawa, Motohiro Tomita, Hirokazu Tatsuoka, Hiroshi Uchiyama, Atsushi Ogura
Summary: The impact of Sn on Si1-xGex was investigated, showing that the thermal conductivity can be reduced by introducing a small amount of Sn. Longitudinal acoustic phonon mode and local vibrations related to Ge structure were observed in the synthesized Si1-x-yGexSny alloy.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Applied
Takefumi Kamioka, Yutaka Hayashi, Kazuhiro Gotoh, Tomohiko Hara, Ryo Ozaki, Motoo Morimura, Ayako Shimizu, Kyotaro Nakamura, Noritaka Usami, Atsushi Ogura, Yoshio Ohshita
Summary: The study successfully extracted the lateral surface inversion layer current in a p-aSi:H/i-aSi:H/cSi heterojunction solar cell through comparison of calculated and experimental results, and obtained parameters related to defect/trap density and acceptor concentration.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Applied
Riku Kobayashi, Toshihide Nabatame, Takashi Onaya, Akihiko Ohi, Naoki Ikeda, Takahiro Nagata, Kazuhito Tsukagoshi, Atsushi Ogura
Summary: In this study, the characteristics of carbon-doped indium oxide thin-film transistors were investigated by varying the O-2 concentration, revealing that the magnitude and direction of bias stress play a crucial role in the positive threshold voltage shift, regardless of the O-2 concentration.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Article
Energy & Fuels
Takeshi Tayagaki, Kikuo Makita, Tomihisa Tachibana, Hidenori Mizuno, Ryuji Oshima, Hidetaka Takato, Takeyoshi Sugaya
Summary: The electrical output characteristics of a three-terminal tandem solar cell were experimentally investigated under different external loading and current mismatch conditions. The results showed that the output power for the two sub-circuits of the three-terminal tandem always added up to the same value, regardless of the chosen loading topology. However, the current-voltage curve of one subcircuit depended on the loading topology and biasing condition of the other sub-circuit.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2021)
Article
Physics, Applied
Masaya Morita, Keiji Ishibashi, Kenichiro Takahashi, Toyohiro Chikyow, Atsushi Ogura, Takahiro Nagata
Summary: The study shows that using ZnxMn1-xS as a buffer layer can facilitate the growth of nonpolar AlN film on a Si (100) substrate, reducing the significant differences between different materials. By inserting an MnS layer between ZnxMn1-xS and Si, it is even possible to achieve film growth of ZnxMn1-xS under metastable conditions and subsequently achieve nonpolar AlN growth.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Article
Nanoscience & Nanotechnology
Sylvia Yuk Yee Chung, Motohiro Tomita, Junya Takizawa, Ryo Yokogawa, Atsushi Ogura, Haidong Wang, Takanobu Watanabe
Summary: The localized phonon-mode spectrum in SiGe alloys changes according to the size distribution of compositional clusters in alloys. By varying the spatial distributions of Si and Ge, alloy models with differing compositions of Si and Ge clusters were produced. A mixture of small and intermediate sized clusters in alloys comprising 20%-80% Ge will give the highest intensities of the local mode.
Article
Physics, Applied
Masaya Morita, Keiji Ishibashi, Kenichiro Takahashi, Shigenori Ueda, Jun Chen, Kota Tatejima, Toyohiro Chikyow, Atsushi Ogura, Takahiro Nagata
Summary: The effects of reactive gas flow conditions on the growth of nonpolar AlN films were investigated. It was found that low-temperature growth prevents unintentional nitridation and results in the crystallization of nonpolar AlN. Additionally, an appropriate N-2 flow improves the crystallinity and reduces defects, suppressing reactions at the interface.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Nanoscience & Nanotechnology
Sylvia Yuk Yee Chung, Motohiro Tomita, Ryo Yokogawa, Atsushi Ogura, Takanobu Watanabe
Summary: Through molecular dynamics simulations, the study examined the impact of atomic mass difference on localized phonon modes in SiGe alloys, revealing that changes in Si and Ge atomic mass can shift the frequency of local modes. It was found that the local mode is sensitive to changes in Si and Ge atomic mass, with the vibration of Si-Ge bonds being the origin of the local mode.
Article
Physics, Applied
Yasushi Hotta, Ryoichi Nemoto, Keisuke Muranushi, Yujun Zhang, Hiroki Wadati, Keita Muraoka, Hiroshi Sakanaga, Haruhiko Yoshida, Koji Arafune, Hitoshi Tabata
Summary: The interface properties of strong correlated electron system/band semiconductor junctions in the La1-xSrxVO3/p-Si(100) structure were investigated. Spectroscopic observations showed that the electronic structure of the interface exhibited insulator/semiconductor junctions for x <= 0.2 and Schottky junctions for x >= 0.25. The energy barriers that could not be explained by spectroscopy were estimated using the thermionic emission model fitting of the forward current density-bias voltage (J-V) characteristics, indicating that the injected carriers from Si to La1-xSrxVO3 can also experience the Coulomb repulsion force at the interface.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Ryo Yokogawa, Yasutomo Arai, Ichiro Yonenaga, Motohiro Tomita, Sylvia Yuk Yee Chung, Hiroshi Uchiyama, Takanobu Watanabe, Atsushi Ogura
Summary: This study reports on the behavior of acoustic phonon spectral linewidth in Si1-xGex alloy with different compositions. Broadening of both transverse acoustic and longitudinal acoustic modes was observed, with the broadening of TA mode depending on the Ge fraction. Molecular dynamics simulations confirmed the experimental observations. These results indicate that the change in acoustic phonon spectral linewidth between Γ and X points is related to the appearance of localized modes in the alloy, leading to suppression of thermal transport.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
K. Cho, N. Sawamoto, H. Machida, M. Ishikawa, H. Sudoh, H. Wakabayashi, R. Yokogawa, A. Ogura
Summary: Large area multi-layer WS2 film shows great potential as a channel material for MOSFETs in next-generation LSIs. To fabricate complex three-dimensional (3D) structures, it is desirable to use CVD to deposit channel layers along a substrate with a complicated 3D structure. In this study, WS2 films were deposited using Metal-Organic CVD and showed stable composition and structure even after 60 days of shelf time in air atmosphere.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Crystallography
Erika Onuma, Takayuki Honda, Hideyuki Yoshimura, Tappei Nishihara, Atsushi Ogura, Nobuyuki Kanzawa, Mamoru Aizawa
Summary: Protein adsorption is crucial for material biocompatibility and cell growth. This study focused on the a-plane structure of hydroxyapatite (HAp) and found that it has a strong protein adsorption ability, particularly proteins related to cellular bone differentiation.
