Article
Chemistry, Physical
Sang Ha Jeong, Thi Kim Oanh Vu, Eun Kyu Kim
Summary: Si-doped Ga2O3 photodetectors were studied with different annealing temperatures, showing that devices annealed at 500 degrees C had the highest photoresponsivity and external quantum efficiency, while devices annealed at 800 degrees C had the fastest switching speeds. These results are attributed to changes in defect densities from chemical bond formation between Si and O atoms.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Materials Science, Ceramics
Chen Wang, Shi-Wei Li, Wei-Hang Fan, Yu-Chao Zhang, Xiao-Ying Zhang, Rong-Rong Guo, Hai-Jun Lin, Shui-Yang Lien, Wen-Zhang Zhu
Summary: This study systematically investigated the evolution of Ga2O3 films deposited on Al2O3(0001) at different substrate temperatures using PLD. By standardizing the thickness of the films, the effect of substrate temperature on the film properties was explored, leading to the production of high-quality crystalline Ga2O3 films suitable for high-performance power electric devices and photoelectronic devices.
CERAMICS INTERNATIONAL
(2021)
Article
Materials Science, Multidisciplinary
Junhee Lee, Honghyuk Kim, Lakshay Gautam, Manijeh Razeghi
Summary: A highly conductive gallium oxide doped with silicon and indium was grown on a c-plane sapphire substrate using MOCVD. The material exhibited high electron hall mobility and carrier concentration when doped with silicon, but was highly resistive without silicon doping. Indium was found to play a role in passivating electron trapping defect levels in the material.
Article
Chemistry, Multidisciplinary
Marianna Spankova, Stefan Chromik, Edmund Dobrocka, Lenka Pribusova Slusna, Marcel Talacko, Maros Gregor, Bela Pecz, Antal Koos, Giuseppe Greco, Salvatore Ethan Panasci, Patrick Fiorenza, Fabrizio Roccaforte, Yvon Cordier, Eric Frayssinet, Filippo Giannazzo
Summary: In this paper, few-layer MoS2 films were prepared on single-crystal sapphire and heteroepitaxial GaN templates on sapphire substrates using pulsed laser deposition (PLD) technique. The films exhibited epitaxial growth and uniform thickness. The electrical current transport and current injection behavior of the films were studied and showed high n-type doping and rectifying behavior.
Article
Materials Science, Multidisciplinary
Armando Hernandez, Md Minhazul Islam, Pooneh Saddatkia, Charles Codding, Prabin Dulal, Sahil Agarwal, Adam Janover, Steven Novak, Mengbing Huang, Tuoc Dang, Mike Snure, F. A. Selim
Summary: Epitaxial Ga2O3 films were grown through MOCVD with optimized growth and doping parameters, showing that electron density and conductivity are influenced by the interplay between dopant concentration, C concentration, and trapping defects in the films. Conductive films with desirable resistivity and mobility for FET and transparent FET applications in DUV technology were successfully obtained.
RESULTS IN PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Xueqiang Xiang, Li-Heng Li, Chen Chen, Guangwei Xu, Fangzhou Liang, Pengju Tan, Xuanze Zhou, Weibing Hao, Xiaolong Zhao, Haiding Sun, Kan-Hao Xue, Nan Gao, Shibing Long
Summary: In this study, high-quality β-Ga2O3 films were epitaxially grown using MOCVD with different donor concentrations, and their shallow donor states were investigated. The unintentional doping effects were found to have a significant impact on the donor states, and a method to reduce the unintentional doping effect was proposed.
SCIENCE CHINA-MATERIALS
(2023)
Article
Physics, Applied
Zhenni Yang, Xiangyu Xu, Yan Wang, Siliang Kuang, Duanyang Chen, Hongji Qi, K. H. L. Zhang
Summary: Si-doped beta-Ga2O3 thin films grown on vicinal a-Al2O3 (0001) substrates exhibit high electrical conductivity and deep ultraviolet (DUV) transparency, making them promising candidates for transparent electrodes. The use of miscut Al2O3 substrates promotes improved crystal quality and electrical properties. The Si-doped films achieved a high conductivity of 37 S cm(-1) and average DUV transparency of 85% on a 6 degrees miscut substrate. The films also exhibit low work function, making them suitable for efficient electron injection in DUV optoelectronic devices.
APPLIED PHYSICS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Hadi Ebrahimi-Darkhaneh, Mahsa Shekarnoush, Josefina Arellano-Jimenez, Rodolfo Rodriguez, Luigi Colombo, Manuel Quevedo-Lopez, Sanjay K. Banerjee
Summary: Epitaxial growth and characterization of Mg-doped Ga2O3 thin films on sapphire substrates using pulsed laser deposition were investigated. The films exhibited p-type semiconducting behavior and an increased band gap compared to pure Ga2O3, making them suitable for applications in ultraviolet photodetectors and power electronic devices.
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
(2022)
Article
Materials Science, Multidisciplinary
Chen Wang, Shi-Wei Li, Yu-Chao Zhang, Wei-Hang Fan, Hai-Jun Lin, Dong-Sing Wuu, Shui-Yang Lien, Wen-Zhang Zhu
Summary: This study systematically investigated the effect of annealing temperature on the texture, optical characters, chemical valence state, and surface topography of amorphous gallium oxide films. The optimal annealing temperature was found to be 700 degrees C, resulting in good crystal quality and flat-continuous surface. However, temperature above 800 degrees C led to the appearance of cracks, possibly due to Al diffusion and thermal expansion coefficient mismatch.
Article
Materials Science, Ceramics
Shaojing Mou, Jiachao Ye, Rongji Zhu, Ruojie Li, Linfei Liu, Yijie Li
Summary: In this study, we investigated the effect of laser repetition rate on the properties of FST superconducting films deposited by pulsed laser deposition. We found that as the laser repetition rate increases, the crystallinity and stoichiometry of the films deteriorate, resulting in a degeneration in superconductivity. However, by increasing the substrate temperature, we were able to successfully deposit high-performance FST films at a high repetition rate.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2024)
Article
Chemistry, Physical
Rovena Veronica Pascu, George Epurescu, Iulian Boerasu, Ana -Maria Banici Niculescu, Dumitru Manica, Alexandra Maria Isabel Trefilov, Bogdan Alexandru Sava
Summary: Samarium doped ceria thin films were successfully deposited on Si (100) substrates at 500 and 600 degrees C using Pulsed Laser Deposition. X-ray Diffraction confirmed the presence of Samarium Doped Cerium Oxide crystalline compound in the films. Atomic Force Microscopy and Scanning Electron Microscopy revealed high quality films with low roughness, especially for the sample deposited at 600 degrees C. X-ray Photoelectron Spectroscopy showed an increased proportion of Ce3+ in the deposited films compared to the target. Spectroscopic Ellipsometry analysis calculated a refractive index under 2.2 in the visible and near-infrared domain. Nanoindentation tribometric measurements indicated a decrease in elasticity modulus and hardness with increasing substrate temperature. These films show potential as electrolyte materials for new generation electrochemical devices.
APPLIED SURFACE SCIENCE
(2022)
Article
Physics, Applied
S. Funada, D. Kan, K. Kuwano, Y. Shiota, R. Hisatomi, T. Moriyama, Y. Shimakawa, T. Ono
Summary: In this study, the temperature dependence of the ferrimagnetic resonance and damping constant of Gd3Fe5O12 films were investigated. The results show that the damping constant is an order of magnitude smaller than those of other ferrimagnetic metals reported so far, highlighting the potential of Gd3Fe5O12 films in ultralow-power spintronic applications.
APPLIED PHYSICS LETTERS
(2022)
Article
Optics
Daqiang Hu, Ying Wang, Yandong Wang, Weiliang Huan, Xin Dong, Jingzhi Yin, Jiang Zhu
Summary: A solar-blind ultraviolet photodetector based on p-Si/n-beta-Ga2O3:Si heterojunction was successfully fabricated using MOCVD, showing good solar-blind ultraviolet photoresponse and relatively faster response speed. The results indicate the potential development of high-performance photodetectors based on p-Si/n-beta-Ga2O3:Si heterojunction.
Article
Physics, Applied
Ta-Shun Chou, Saud Bin Anooz, Raimund Grueneberg, Natasha Dropka, Jana Rehm, Thi Thuy Vi Tran, Klaus Irmscher, Palvan Seyidov, Wolfram Miller, Zbigniew Galazka, Martin Albrecht, Andreas Popp
Summary: (English Summary:)
This study proposes a Langmuir adsorption model for the Si incorporation mechanism into (100) beta-Ga2O3 thin films grown by metalorganic vapor-phase epitaxy, based on the competitive surface adsorption process between Si and Ga atoms. The model describes the major features of the doping process and shows a growth rate-dependent doping behavior, which is experimentally validated and further generalized to different growth conditions and substrate orientations.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Condensed Matter
Ji-Hoon Kang, Jihyun Kim, Tae Beom Park, Woo Seok Choi, Sungmin Park, Tuson Park
Summary: We report the growth of CeIrIn5 thin films with different crystal orientations on a MgF2 (001) substrate using the pulsed laser deposition technique. The characteristic features of heavy-fermion superconductors, including Kondo coherence and superconductivity, were observed in the thin films. The successful synthesis of CeIrIn5 thin films is expected to provide a new avenue for exploring novel quantum phases.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
Article
Energy & Fuels
Tooru Tanaka, Shuji Tsutsumi, Katsuhiko Saito, Qixin Guo, Kin Man Yu
Summary: By doping Cl-doped ZnTeO, the photocurrent induced by two-step photon absorption in intermediate band solar cells is significantly improved. The high activation energy of Cl donor increases the activation temperature of TSPA current, while the introduction of electrons by Cl doping helps improve the open circuit voltage of IBSCs.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2022)
Article
Materials Science, Multidisciplinary
Jiani Lv, Wenning Zhao, Wenhui Li, Jiatao Yu, Mingzhe Zhang, Xiuxun Han, Tooru Tanaka
Summary: This article demonstrates a gradient cooling process to improve the structural defects in all-inorganic perovskite films and enhance charge carrier transport by reducing defect density. The results show promising application prospects for this method in all-inorganic perovskite films without a dopant/additive.
JOURNAL OF MATERIALS CHEMISTRY C
(2022)
Article
Optics
Zewei Chen, Katsuhiko Saito, Tooru Tanaka, Qixin Guo
Summary: Near-infrared (NIR) light-emitting diodes (LEDs) based on Tm-Ga2O3/GaAs were fabricated and characterized. The strongest NIR emission at 794 nm and the major blue emission at 476 nm were observed, with different turn-on voltages. These results provide insights for the development of Ga(2)O(3)-based LEDs for NIR applications.
JOURNAL OF LUMINESCENCE
(2022)
Article
Optics
Yafei Huang, Katsuhiko Saito, Tooru Tanaka, Qixin Guo
Summary: In this study, Eu doped Ga2O3 thin films were prepared and the influence of thermal annealing temperature and ambient on their optical and structural properties was investigated. The results showed that annealing in an oxygen ambient at 600 degrees C significantly enhanced the red luminescence of Ga2O3:Eu. Higher Eu concentrations in the films also led to stronger photoluminescence enhancement, providing a method to suppress concentration quenching. This study has potential implications for the development of highly efficient red light-emitting devices based on Ga2O3:Eu films.
JOURNAL OF LUMINESCENCE
(2022)
Article
Chemistry, Multidisciplinary
HyoChang Jang, Katsuhiko Saito, Qixin Guo, Kin Man Yu, Tooru Tanaka
Summary: The effects of Al doping on the properties of RS-ZnCdO thin films were studied. It was found that Al incorporation led to single-crystal layers and increased electron concentration. The films with Al doping exhibited a high optical bandgap, making them suitable for transparent conductors in full-spectrum solar cells.
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
(2022)
Article
Chemistry, Physical
Fabi Zhang, Jin Zhang, Lijie Huang, Shangfeng Liu, Wei Luo, Junjie Kang, Zhiwen Liang, Jiakang Cao, Chenhui Zhang, Qi Wang, Ye Yuan
Summary: In this study, epitaxial semipolar (11-22) AlN was successfully prepared on nonpolar m-sapphire substrate using sputtering and high-temperature annealing. The evolution of crystalline structure and morphology was investigated by measurements and analysis, showing that annealing improved the crystalline quality. The influence of AlN-sapphire interface on crystalline quality and lattice parameters during annealing was found to be less significant with increasing film thickness. The annealing duration had no effect on crystalline quality but had a noticeable impact on morphology, indicating that crystalline reorganization occurs before morphology reset. The zig-zag morphology of the AlN template along the sapphire [0001] direction, resulting from annealing, could affect the subsequent device epitaxy process.
Article
Multidisciplinary Sciences
Md Alauddin Hossain, Syed Farid Uddin Farhad, Nazmul Islam Tanvir, Jang Hyo Chang, Mohammad Atiqur Rahman, Tooru Tanaka, Qixin Guo, Jamal Uddin, Md Abdul Majed Patwary
Summary: In this study, Cu2O nanorods were deposited on soda-lime glass substrates using the modified successive ionic layer adsorption and reaction technique. The synthesized Cu2O nanorod films were characterized for their structural, electrical, and optical properties. The presence of NaCl electrolyte in the precursor solutions was found to have a significant impact on the physical properties of Cu2O nanorod films.
ROYAL SOCIETY OPEN SCIENCE
(2022)
Article
Physics, Applied
Yafei Huang, Gaofeng Deng, Katsuhiko Saito, Tooru Tanaka, Qixin Guo
Summary: In this study, we demonstrated an LED based on Tm, Er, and Eu codoped Ga2O3 thin film. By intentionally changing the concentrations of Tm3+, Er3+, and Eu3+ ions, we achieved simultaneous emission of blue, green, and red light, showing great potential for full-color light emission.
APPLIED PHYSICS EXPRESS
(2022)
Article
Materials Science, Multidisciplinary
Zewei Chen, Katsuhiko Saito, Tooru Tanaka, Qixin Guo
Summary: High-quality body-centered cubic In2O3 films were grown on a-plane sapphire substrates using pulsed laser deposition. The films exhibited a good crystalline quality, high carrier concentration, and a wide bandgap. The properties of the films were affected by the substrate temperature.
Article
Materials Science, Multidisciplinary
Gaofeng Deng, Yafei Huang, Zewei Chen, Katsuhiko Saito, Tooru Tanaka, Makoto Arita, Qixin Guo
Summary: Rutile germanium oxide (r-GeO2) film was successfully grown heteroepitaxially on c-plane sapphire through pulsed laser deposition. The film's chemical composition, structure, surface morphology, optical properties, and crystal quality were comprehensively investigated. The results revealed that the film had a rutile structure with a good orientation, and exhibited transparent properties and a wide bandgap, which are significant for the development of wide-bandgap r-GeO2 films for electronic devices.
Article
Multidisciplinary Sciences
Zhan Hua Li, Jia Xing He, Xiao Hu Lv, Ling Fei Chi, Kingsley O. Egbo, Ming-De Li, Tooru Tanaka, Qi Xin Guo, Kin Man Yu, Chao Ping Liu
Summary: Copper iodide, as a promising high mobility p-type wide bandgap semiconductor, has attracted increasing attention. However, the defect physics/evolution and ultrafast carrier and exciton dynamics in copper iodide are still controversial and rarely investigated. In this study, the fundamental properties of copper iodide thin films are investigated using a combination of analytical techniques. The results provide insights into the photogenerated carrier density dependent ultrafast physical processes and the effects of defects on carrier recombination and two-photon induced ultrafast carrier dynamics. These findings are crucial for the optoelectronic applications of copper iodide.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Tooru Tanaka, Ryusuke Tsutsumi, Tomohiro Yoshinaga, Takaki Sonoyama, Katsuhiko Saito, Qixin Guo, Shigeru Ikeda
Summary: The PEC properties of ZnTe-based photocathodes with various structures were investigated, and it was found that samples with heterostructures showed better performance than those without heterojunctions. In particular, the n-ZnS/ZnTe/p-ZnTe sample exhibited excellent performance even at low applied potential in the presence of Eu3+ ions.
Article
Chemistry, Physical
Xiao Hu Lv, Zhan Hua Li, Yuan Shen Qi, Tooru Tanaka, Qi Xin Guo, Kin Man Yu, Chao Ping Liu
Summary: Amorphous p-type transparent (Ga2O3)1-x(Cu2S)x alloy thin films with x<-0.5 have been successfully synthesized by magnetron sputtering at room temperature in this study. The optical bandgap decreases from -4.8 eV to -2.5 eV with increasing x, while the hole concentration N increases from 1019 cm-3 to -2 x 1021 cm-3, with a hole mobility of -0.3 cm2 V-1 s-1. The hole transport in these amorphous alloys follows the variable-range-hopping mechanism in the temperature range of 120-300 K. The upshift of the valence band maximum (VBM) position by -3 eV with x > 0.2 enhances the p-type conductivity of the films. These amorphous p-type transparent (Ga2O3)1-x(Cu2S)x alloy thin films show potential significance in bipolar device applications, such as Ga2O3 based p-n heterojunction power devices and high-efficiency solar cells.
APPLIED SURFACE SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Qixin Guo, Junya Tetsuka, Zewei Chen, Makoto Arita, Katsuhiko Saito, Tooru Tanaka
Summary: MgGa2O4 films were grown on sapphire substrates at different substrate temperatures using pulsed laser deposition technique. The influence of substrate temperature on the properties of the films was systematically investigated. Deep ultraviolet (DUV) photodetectors based on these films exhibited excellent performance, indicating the potential for novel optoelectronic applications.
