Article
Materials Science, Coatings & Films
Jacqueline Cooke, Praneeth Ranga, Arkka Bhattacharyya, Xueling Cheng, Yunshan Wang, Sriram Krishnamoorthy, Michael A. Scarpulla, Berardi Sensale-Rodriguez
Summary: We report the discovery of a new type of structural defect in beta-Ga2O3 homoepitaxial thin films, which we call sympetalous defects. These defects consist of a line defect in the substrate combined with a multi-faceted inverted polycrystalline pyramid in the epitaxial film. Photoluminescence microscopy revealed polarization-dependent luminescence and circular dichroism at these defects. Understanding and controlling these defects is important for modifying film properties, affecting device yields, and influencing characterization experiments.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Materials Science, Coatings & Films
Lingyu Meng, A. F. M. Anhar Uddin Bhuiyan, Zixuan Feng, Hsien-Lien Huang, Jinwoo Hwang, Hongping Zhao
Summary: In this study, the MOCVD growth of (100) beta-Ga2O3 on on-axis Ga2O3 substrates was comprehensively investigated. The dependence of growth conditions on surface morphology, growth rate, and electron transport properties of the thin films was studied. The results provide a fundamental understanding of MOCVD epitaxy and the limitations of electron transport properties in (100) beta-Ga2O3 thin films grown along the on-axis (100) crystal orientation.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2022)
Article
Nanoscience & Nanotechnology
Ta-Shun Chou, Palvan Seyidov, Saud Bin Anooz, Raimund Grueneberg, Thi Thuy Vi Tran, Klaus Irmscher, Martin Albrecht, Zbigniew Galazka, Jutta Schwarzkopf, Andreas Popp
Summary: The study successfully achieved a high growth rate and high crystalline perfection for Si-doped (100) beta-Ga2O3 homoepitaxial films grown via MOVPE. Si doping allowed precise control of the n-type conductivity of the films, providing a critical technological advancement for high power electronics.
Article
Engineering, Electrical & Electronic
Di Wang, Xiaochen Ma, Hongdi Xiao, Yong Le, Jin Ma
Summary: This study successfully prepared epitaxial beta-Ga2O3 films with different Ta doping concentrations, showcasing the ability to control carrier concentration and electrical properties by adjusting Ta concentration. The obtained films exhibited high quality single crystal structure and excellent transmittance in the visible light region.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Zeming Li, Teng Jiao, Wancheng Li, Gaoqiang Deng, Wei Chen, Zhengda Li, Zhaoti Diao, Xin Dong, Baolin Zhang, Yuantao Zhang, Zengjiang Wang, Guotong Du
Summary: Beta-Ga2O3 is a promising material for solar-blind UV detection, and the crystal quality significantly affects the performance of photodetectors. In this study, high quality homoepitaxial beta-Ga2O3 films were grown by MOCVD for SBUV PD fabrication, demonstrating excellent performance for both photoconductor PD and SBD PD. The responsivity and EQE of photoconductor PD were 1.08 A/W and 5.32 x 102% under 254nm illumination, while the I-254/Idark and rejection ratio of SBD PD were 320 and 42, respectively.
Article
Physics, Applied
T. D. Gustafson, J. Jesenovec, C. A. Lenyk, N. C. Giles, J. S. McCloy, M. D. McCluskey, L. E. Halliburton
Summary: Electron paramagnetic resonance (EPR) is utilized to identify and characterize neutral zinc acceptors in Zn-doped beta-Ga2O3 crystals. The study reveals the presence of two types of Zn acceptors, Zn-Ga (0)(1) and Zn-Ga (0)(2), and investigates their interactions and thermal stability.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Nanoscience & Nanotechnology
Hyung Min Jeon, Kevin D. Leedy, David C. Look, Celesta S. Chang, David A. Muller, Stefan C. Badescu, Vladimir Vasilyev, Jeff L. Brown, Andrew J. Green, Kelson D. Chabak
Summary: This study successfully synthesized conductive Si-doped beta-Ga2O3 homoepitaxial films with high transparency and promising applications using pulsed laser deposition.
Article
Physics, Applied
I. Stenger, M. -A. Pinault-Thaury, N. Temahuki, R. Gillet, S. Temgoua, H. Bensalah, E. Chikoidze, Y. Dumont, J. Barjon
Summary: This study investigates electron transport in n-type diamond using phosphorus-doped (100) homoepitaxial layers in the range of 10^16-10^18 cm^-3. The electrical properties of the n-type layers, including electron concentration and mobility, were measured as a function of temperature. Modeling of electron scattering in diamond for the (100) orientation, which is favored for electronic device applications, was carried out. The physical parameters extracted from experimental data fitting provide insight into the upper limit for electron mobility in (100) n-type diamond.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Jinying Yu, Yi Yu, Zhiqiang Bai, Yan Peng, Xiaoyan Tang, Xiaobo Hu, Xuejian Xie, Xiangang Xu, Xiufang Chen
Summary: The surface morphologies and microstructures of triangular defects in 4H-SiC homoepitaxial layers were investigated. Three different defect types, TD-I (grains), TD-II (micro-pits), and TD-III (washboard-like defects), were analyzed. The formation mechanisms were identified to be related to partial dislocations, etch pits, micropipes, and dislocations. High-resolution transmission electron microscopy, micro-Raman spectroscopy, and photoluminescence spectroscopy were used for characterization.
Article
Nanoscience & Nanotechnology
Ymir K. Frodason, Patryk P. Krzyzaniak, Lasse Vines, Joel B. Varley, Chris G. Van de Walle, Klaus Magnus H. Johansen
Summary: The diffusion of the n-type dopant Sn in beta-Ga2O3 was studied using secondary-ion mass spectrometry combined with hybrid functional calculations. It was found that Ga vacancies mediate the migration of Sn through the formation and dissociation of intermittent mobile VGaSnGa complexes. The migration barrier for the VGaSnGa complex was determined to be 3.0 +/- 0.4 eV, consistent with theoretical predictions using the nudged elastic band method.
Article
Materials Science, Multidisciplinary
Teng Jiao, Zeming Li, Wei Chen, Xin Dong, Zhengda Li, Zhaoti Diao, Yuantao Zhang, Baolin Zhang
Summary: The use of silane as an n-type dopant for Si-doped beta-Ga2O3 films grown on (100) beta-Ga2O3 substrates via MOCVD allows for stable control of electron concentrations, with higher quality and lower defect density observed in homoepitaxial compared to heteroepitaxial films. Increasing doping concentration may adversely affect defect density and surface morphology of the films.
Article
Chemistry, Multidisciplinary
Alex Sandre Kilian, Abner de Siervo, Richard Landers, Guilherme Jean P. Abreu, Mayron S. Castro, Tyson Back, Alexandre Pancotti
Summary: In this study, a comprehensive investigation of the surface atomic structure of beta-Ga2O3 (100) was conducted using simulations and in situ characterizations. The results revealed significant structural variations in the interatomic layer, which may explain the observed electronic phenomena in theoretical studies. Comparison between experimental and theoretical results indicated that the beta-Ga2O3 surface has two possible terminations.
Article
Physics, Condensed Matter
Wenbo Tang, Xueli Han, Xiaodong Zhang, Botong Li, Yongjian Ma, Li Zhang, Tiwei Chen, Xin Zhou, Chunxu Bian, Yu Hu, Duanyang Chen, Hongji Qi, Zhongming Zeng, Baoshun Zhang
Summary: This study investigates the homoepitaxial growth of Si-doped beta-Ga2O3 films on semi-insulating (100) beta-Ga2O3 substrates using metalorganic chemical vapor deposition (MOCVD). By optimizing the growth conditions, the diffusion length of Ga adatoms is increased, resulting in suppressed 3D island growth patterns and improved surface morphology. The Si-doped beta-Ga2O3 film demonstrates high crystal quality, smooth surface morphology, and effective Si doping.
JOURNAL OF SEMICONDUCTORS
(2023)
Article
Physics, Applied
Takeshi Kimura, Taichiro Konno, Hajime Fujikura
Summary: The presence of electron traps and residual carbon, as well as their trade-off relationship, poses a challenge in fabricating next-generation GaN-based power devices using the metal-organic chemical vapor deposition (MOCVD) method. By utilizing the hydride vapor phase epitaxy (HVPE) method and making modifications to the process, the concentration of residual carbon and major electron traps in GaN layers can be significantly reduced, resulting in improved optical and electrical properties without a trade-off relationship.
APPLIED PHYSICS LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Arpit Nandi, David Cherns, Indraneel Sanyal, Martin Kuball
Summary: Heteroepitaxial growth of beta-Ga2O3 on (001) diamond by MOCVD was achieved, and the epitaxial relationship and crystal structure were studied using TEM.
CRYSTAL GROWTH & DESIGN
(2023)
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, Applied
Ta-Shun Chou, Palvan Seyidov, Saud Bin Anooz, Raimund Grueneberg, Mike Pietsch, Jana Rehm, Thi Thuy Vi Tran, Kornelius Tetzner, Zbigniew Galazka, Martin Albrecht, Klaus Irmscher, Andreas Fiedler, Andreas Popp
Summary: This study investigated the MOVPE of (100) beta-Ga2O3 films for high-power electronic devices. A height-adjustable showerhead close to the susceptor was crucial in increasing the stability of the Ga wetting layer on the surface and reducing parasitic particles. The achieved film thickness was up to 3 μm with a low root mean square value, and record carrier mobilities were observed at room temperature.
APPLIED PHYSICS LETTERS
(2023)
Article
Crystallography
Detlef Klimm, Binderiya Amgalan, Steffen Ganschow, Albert Kwasniewski, Zbigniew Galazka, Matthias Bickermann
Summary: This paper presents laser flash measurements of the thermal conductivity of Czochralski-grown beta-Ga2O3 single crystals along different crystallographic lattice planes. The results show that the thermal conductivity has orientation dependence and varies with temperature.
CRYSTAL RESEARCH AND TECHNOLOGY
(2023)
Article
Physics, Applied
Ta-Shun Chou, Palvan Seyidov, Saud Bin Anooz, Raimund Grueneberg, Jana Rehm, Tran Thi Thuy Vi, Andreas Fiedler, Kornelius Tetzner, Zbigniew Galazka, Martin Albrecht, Andreas Popp
Summary: In this study, the development of unwanted parasitic particles in the MOVPE chamber during the growth of mu m level films is comprehensively investigated. The density of parasitic particles is observed to be significant at film thicknesses starting from >1.5 to 2 mu m. These particles induce structural defects, such as twin lamellae, which adversely affect the electrical properties of the grown film. The parasitic particles originate from parasitic reactions within the chamber triggered by the promoted gas-phase reactions during the growth process, and their density can be reduced by increasing total gas flow and reducing the showerhead distance to the susceptor. After minimizing the density of parasitic particles, film thicknesses up to 4 mu m have been achieved. RT Hall measurements reveal carrier mobilities of 160 cm(2)V(-1)s(-1) at carrier concentrations of 5.7 x 10(16) cm(-3).
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Zbigniew Galazka, Andreas Fiedler, Andreas Popp, Steffen Ganschow, Albert Kwasniewski, Palvan Seyidov, Mike Pietsch, Andrea Dittmar, Saud Bin Anooz, Klaus Irmscher, Manuela Suendermann, Detlef Klimm, Ta-Shun Chou, Jana Rehm, Thomas Schroeder, Matthias Bickermann
Summary: We studied the growth and physical properties of β-(AlxGa1-x)(2)O-3 single crystals with different Al contents using the Czochralski method. The Al segregation coefficient in the Ga2O3 melt resulted in higher Al content in the crystals. By co-doping with Si or Mg, we obtained semiconducting, degenerately semiconducting, or semi-insulating crystals. The lattice constants decreased anisotropically, while the optical bandgap increased linearly with Al content.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Crystallography
Ta-Shun Chou, Saud Bin Anooz, Raimund Grueneberg, Thuy Vi Thi Tran, Jana Rehm, Zbigniew Galazka, Andreas Popp
Summary: Si-doped beta-Ga2O3 layers were grown on (100) beta-Ga2O3 semi-insulating substrates by MOVPE, and their reflection spectrum on the substrate surface was investigated. Transforming the reflectance spectrum into the autocorrelation domain revealed a more pronounced Fabry-Pe 'rot oscillation, which allowed for easy estimation of the growth rate and growth mode based on the period and damping behavior of the spectrum. The observed oscillation contributed to the refractive index difference between the substrate and the film caused by impurities and preparation techniques. The high sensitivity of reflectance spectroscopy demonstrated its advantage as a powerful growth process monitoring tool.
JOURNAL OF CRYSTAL GROWTH
(2023)
Article
Physics, Applied
Kornelius Tetzner, Michael Klupsch, Andreas Popp, Saud Bin Anooz, Ta-Shun Chou, Zbigniew Galazka, Karina Ickert, Mathias Matalla, Ralph-Stephan Unger, Eldad Bahat Treidel, Mihaela Wolf, Achim Trampert, Joachim Wuerfl, Oliver Hilt
Summary: In this work, vertical (100) beta-Ga2O3 FinFET devices were realized for power electronics applications. The devices were fabricated on highly conducting (100) beta-Ga2O3 substrates and epitaxially grown layers with specific doping concentrations for the drift and channel regions. The fabricated FinFET devices showed enhancement-mode properties and measured breakdown strength.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Engineering, Electrical & Electronic
Aravind Subramanian, Nikolay Abrosimov, Alexander Gybin, Christo Guguschev, Uta Juda, Andreas Fiedler, Florian Baerwolf, Ioan Costina, Albert Kwasniewski, Andrea Dittmar, R. Radhakrishnan Sumathi
Summary: Highly doped germanium (HD-Ge) is a promising material for various devices, and an effective method of doping germanium ingots in the Czochralski growth process needs to be developed. In this study, highly doped Ge crystals were grown by the Cz technique and the distribution of dopants followed the predicted profile. The crystals showed good structural quality as confirmed by x-ray diffraction rocking curve measurements.
JOURNAL OF ELECTRONIC MATERIALS
(2023)
Article
Materials Science, Coatings & Films
Kornelius Tetzner, Andreas Thies, Palvan Seyidov, Ta-Shun Chou, Jana Rehm, Ina Ostermay, Zbigniew Galazka, Andreas Fiedler, Andreas Popp, Joachim Wuerfl, Oliver Hilt
Summary: In this study, the optimum annealing conditions for activating Ge-implanted beta-Ga2O3 were analyzed to achieve low ohmic contact resistances. Pulsed rapid thermal annealing treatment was conducted at temperatures between 900 and 1200 degrees C in a nitrogen atmosphere. The results showed that high-temperature annealing above 1000 degrees C led to increased surface roughness and significant redistribution of implanted Ge. However, annealing at 1100 degrees C resulted in a significant reduction in specific contact resistance, reaching a record value of 4.8 x 10(-7) Omega cm(2) with an implantation activation efficiency of 14.2%. The highest activation efficiency of 19.2% and lowest sheet resistances were achieved at 1200 degrees C, but the ohmic contact properties were inferior due to severe increase in surface roughness. These findings demonstrate the high potential of high-temperature annealing processes above 1000 degrees C for achieving low ohmic contact resistances in beta-Ga2O3.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Physics, Applied
Sushovan Dhara, Ashok Dheenan, Nidhin Kurian Kalarickal, Hsien-Lien Huang, Ahmad Ehteshamul Islam, Chandan Joishi, Andreas Fiedler, Joe F. McGlone, Steven A. Ringel, Jinwoo Hwang, Siddharth Rajan
Summary: This work investigates the plasma-assisted deposition of Al2O3 on HVPE (001) beta-Ga2O3 and evaluates the dielectric quality through electrical measurements on fabricated MOS capacitors. The interface structure and crystallinity of the films are studied as a function of the growth temperature. The study demonstrates the advantage of using plasma-assisted deposition to achieve high breakdown strength Al2O3/beta-Ga2O3 MOS structures for device applications.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
V. Bonito Oliva, D. Mangelinck, S. Hagedorn, H. Bracht, K. Irmscher, C. Hartmann, P. Vennegues, M. Albrecht
Summary: In this study, the diffusion of Si donors in AlN is investigated. The experiments show that Si diffusion in AlN is mediated by singly negatively charged dopant-vacancy pairs SiAlVAl-. The strong concentration dependence of Si diffusion can be attributed to the electric field associated with the incorporation of Si donors on substitutional Al lattice sites.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Wahib Aggoune, Alberto Eljarrat, Dmitrii Nabok, Klaus Irmscher, Martina Zupancic, Zbigniew Galazka, Martin Albrecht, Christoph Koch, Claudia Draxl
Summary: The perovskite barium stannate (BaSnO3) shows promise for electronic applications due to its transparency and high room-temperature mobility. A combined theoretical and experimental study provides a consistent picture of its electronic structure and optical excitations.
COMMUNICATIONS MATERIALS
(2022)
