Article
Physics, Applied
Hironori Okumura
Summary: The critical layer thickness for (AlGa) (2) O-3 heteroepitaxial growth on beta-Ga2O3 (010) substrates via plasma-assisted molecular beam epitaxy was reported, along with the electrical properties of heavily tin-doped (AlGa) (2) O-3 layers. The aluminum composition in the (AlGa) (2) O-3 layers was reproducibly controlled within 19% by changing aluminum fluxes. Pseudomorphic growth of (Al0.12Ga0.88) (2) O-3 and (Al0.15Ga0.85) (2) O-3 layers of certain thicknesses on beta-Ga2O3 (010) substrates was achieved.
JAPANESE JOURNAL OF APPLIED PHYSICS
(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
Nanoscience & Nanotechnology
Karim Ben Saddik, Basilio J. Garcia, Sergio Fernandez-Garrido
Summary: In this study, the chemical beam epitaxy of GaP1-xNx alloys was investigated, revealing that the N mole fraction exhibits an Arrhenius behavior in relation to growth temperature and precursor fluxes. The results indicate the feasibility of obtaining single-phase and flat GaP1-xNx layers with x up to about 0.04.
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
Nanoscience & Nanotechnology
Arkka Bhattacharyya, Carl Peterson, Takeki Itoh, Saurav Roy, Jacqueline Cooke, Steve Rebollo, Praneeth Ranga, Berardi Sensale-Rodriguez, Sriram Krishnamoorthy
Summary: We demonstrate a new substrate cleaning and buffer growth scheme in beta-Ga2O3 epitaxial thin films using MOVPE. By growing a low-temperature un-doped Ga2O3 buffer followed by a transition layer to high-temperature Si-doped Ga2O3 channel layers, continuous growth of the channel structure was achieved. The parasitic Si channel at the epilayer-substrate interface was effectively compensated through solvent cleaning and hydrofluoric acid treatment. This substrate cleaning combined with the LT buffer scheme shows the potential for designing Si-doped beta-Ga2O3 channels with exceptional transport properties.
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
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
Hiroyuki Nishinaka, Tatsuji Nagaoka, Yuki Kajita, Masahiro Yoshimoto
Summary: Utilizing mist chemical vapor deposition (CVD) process, rapid homoepitaxial growth of beta-Ga2O3 thin films with smooth surfaces was achieved using a concentrated aqueous solution of GaCl3 precursor.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2021)
Article
Nanoscience & Nanotechnology
Timothy A. Morgan, Justin Rudie, Mohammad Zamani-Alavijeh, Andrian V. Kuchuk, Nazar Orishchin, Fikadu Alema, Andrei Osinsky, Robert Sleezer, Gregory Salamo, Morgan E. Ware
Summary: The band offsets for the beta-(Al0.21Ga0.79)(2)O-3/beta-Ga2O3 (010) heterojunction were experimentally measured, and the resulting band alignment was determined to be of type II. These findings provide valuable data for the design and prediction of beta-(AlxGa1-x)(2)O-3 heterojunction-based devices.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Nanoscience & Nanotechnology
Hemant Ghadi, Joe F. McGlone, Evan Cornuelle, Zixuan Feng, Yuxuan Zhang, Lingyu Meng, Hongping Zhao, Aaron R. Arehart, Steven A. Ringel
Summary: This study evaluates the defect state distribution in beta phase gallium oxide (beta-Ga2O3) grown by low-pressure chemical vapor deposition (LPCVD). The presence of a previously unreported defect state and other known defect states were observed. The trap concentration in the LPCVD-grown material was lower compared to materials grown by other methods, and the distribution of the defect states showed little dependence on the SiCl4 flow rate and doping concentration. These findings indicate that LPCVD-grown beta-Ga2O3 has great potential for producing thick, low-defect density, and high-quality layers for multi-kV device applications.
Article
Physics, Applied
F. Egyenes, F. Gucmann, A. Rosova, E. Dobrocka, K. Husekova, F. Hrubisak, J. Keshtkar, M. Tapajna
Summary: A significant anisotropy in electrical conductance was observed in Si-doped alpha-Ga2O3/sapphire samples grown via liquid-injection metal organic chemical vapor deposition. X-ray diffraction (XRD) revealed the presence of (010) beta-Ga2O3 in addition to epitaxial alpha-Ga2O3. Various characterization techniques confirmed the formation of (010) beta-Ga2O3 filaments in undoped alpha-Ga2O3 film. Conductive AFM and current-voltage measurements confirmed the higher conductivity along the [2(1)(1)0] alpha-Ga2O3 direction compared to [0001] alpha-Ga2O3 direction, attributed to the presence of beta-Ga2O3 filaments.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Crystallography
Jiulong Wang, Siqi Zhao, Guoguo Yan, Zhanwei Shen, Wanshun Zhao, Lei Wang, Xingfang Liu
Summary: In this study, wafer-scale on-axis 4H-SiC epitaxial layers with very low roughness were obtained. Local mirror regions (LMRs) with RMS roughness less than 0.2 nm were observed on the epitaxial layer surface. The growth mechanism and the effect of etching pits on the growth rate of epitaxial layers were investigated.
Article
Physics, Applied
Sudipto Saha, Lingyu Meng, Zixuan Feng, A. F. M. Anhar Uddin Bhuiyan, Hongping Zhao, Uttam Singisetti
Summary: This paper presents a systematic study on the Schottky diodes fabricated on Si-doped homoepitaxial beta-Ga2O3 thin films grown on different substrates by LPCVD. The results show that higher temperature growth leads to the highest growth rate and the characteristics of the diodes are analyzed and studied.
APPLIED PHYSICS LETTERS
(2022)
Article
Materials Science, Multidisciplinary
V. Mortet, A. Taylor, N. Lambert, Z. Gedeonova, L. Fekete, J. Lorincik, L. Klimsa, J. Kopecek, P. Hubik, Z. Soban, A. Laposa, M. Davydova, J. Voves, A. Posta, V. Povolny, P. Hazdra
Summary: The study reported on the structural and electrical properties of boron-doped epitaxial diamond layers grown on (113) substrates. The results showed that these diamond layers can be grown at high deposition rates with atomically flat surfaces, excellent electrical properties, and high boron incorporation efficiency.
DIAMOND AND RELATED MATERIALS
(2021)
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
Physics, Applied
S. Bin Anooz, R. Grueneberg, T-S Chou, A. Fiedler, K. Irmscher, C. Wouters, R. Schewski, M. Albrecht, Z. Galazka, W. Miller, J. Schwarzkopf, A. Popp
Summary: The study investigated the impact of chamber pressure and Si-doping on the growth of beta-Ga2O3 thin films, resulting in changes in growth modes and electron mobility. High-quality homoepitaxial thin films of beta-Ga2O3 were obtained under optimal conditions.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Physics, Applied
Leonardo Cancellara, Toni Markurt, Tobias Schulz, Martin Albrecht, Sylvia Hagedorn, Sebastian Walde, Markus Weyers, Shun Washiyama, Ramon Collazo, Zlatko Sitar
Summary: This study investigates the recovery process of epitaxial AlN films on sapphire at high temperatures. It reveals a temperature-dependent increase in oxygen content and proposes a lateral outdiffusion hypothesis to explain the observed oxygen concentration plateaus. Additionally, it concludes that the di-oxygen/aluminum vacancy complex (V-Al-2O(N)) plays a key role in controlling the annealing process.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Applied
A. F. M. Anhar Uddin Bhuiyan, Zixuan Feng, Lingyu Meng, Andreas Fiedler, Hsien-Lien Huang, Adam T. Neal, Erich Steinbrunner, Shin Mou, Jinwoo Hwang, Siddharth Rajan, Hongping Zhao
Summary: This work investigates the structural and electrical properties of metalorganic chemical vapor deposited Si-doped beta-(AlxGa1-x)(2)O-3 thin films grown on (010) beta-Ga2O3 substrates as a function of Al composition. The results show that increasing Al composition leads to a decrease in Si incorporation efficiency, an increase in C and H impurity levels, and lower net carrier concentrations in the films. Higher Al compositions also result in cracking in the films due to lattice mismatch with the substrate. The study highlights the importance of Al composition in determining the properties of Si-doped beta-(AlxGa1-x)(2)O-3 films.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
L. Cancellara, S. Hagedorn, S. Walde, D. Jaeger, M. Albrecht
Summary: The structural recovery of AlN grown on a sapphire substrate during high-temperature annealing is studied. The as-grown film shows high-density planar defects and nanopipes, which have a significant influence on the structural recovery.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Alexandra Papadogianni, Charlotte Wouters, Robert Schewski, Johannes Feldl, Jonas Lahnemann, Takahiro Nagata, Elias Kluth, Martin Feneberg, Rudiger Goldhahn, Manfred Ramsteiner, Martin Albrecht, Oliver Bierwagen
Summary: In this study, single-crystalline bixbyite (In1-xGax)(2)O-3 films were grown on (111)-oriented yttria-stabilized zirconia substrates using plasma-assisted molecular beam epitaxy. The addition of a pure In2O3 buffer layer between the substrate and (In1-xGax)(2)O-3 alloy improved the film surface smoothness and crystallinity. The distribution of Ga cations in the films was found to be non-uniform, with high Ga density inclusions observed at higher Ga content. The cubic bixbyite phase was preserved in both the matrix and the inclusions.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Physics, Applied
Jana Rehm, Ta-Shun Chou, Saud Bin Anooz, Palvan Seyidov, Andreas Fiedler, Zbigniew Galazka, Andreas Popp
Summary: This study provides an overview of the applications of MOVPE-grown (100) beta-Ga2O3 thin films in high-power electronics and discusses the challenges faced. Through analyzing the structural defect formation mechanism, substrate treatment strategies, and growth windows, the grown film was optimized to meet the requirements for device fabrication. Furthermore, this study proposes strategies for future growth process optimization.
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
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
Nanoscience & Nanotechnology
Palvan Seyidov, Joel B. Varley, Zbigniew Galazka, Ta-Shun Chou, Andreas Popp, Andreas Fiedler, Klaus Irmscher
Summary: Optical absorption and photoconductivity measurements of Co-doped beta-Ga2O3 crystals reveal the photon energies of optically excited charge transfer between the Co related deep levels and the conduction or valence band. The results show that Co doping is promising for producing semi-insulating beta-Ga2O3 crystals, with consistent thermal activation energy of 2.1 +/- 0.1 eV for the Co acceptor level.
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)
