Article
Materials Science, Ceramics
Yutaro Katsuyama, Ayu Kodaira, Tomoharu Tokunaga, Takahisa Yamamoto
Summary: By annealing the (001) surfaces of SrTiO3 single crystal with fully terminated TiO2 atomic layer, SrO-terminated terraces were formed along TiO2-terminated step edges. Using scanning electron microscopy, the step-terrace structures with different terminations were visualized, and the uniformity of the structures was found to be limited to localized areas with many step-defects.
JOURNAL OF THE CERAMIC SOCIETY OF JAPAN
(2023)
Article
Chemistry, Physical
Arifumi Okada, Masahiro Nakatani, Lei Chen, Romualdo A. Ferreyra, Kohei Kadono
Summary: The bulk properties of beta-Ga2O3 are sensitive to temperature and atmosphere, and suitable annealing conditions are required. Different annealing conditions resulted in different surface morphologies, highlighting the need for optimized annealing conditions based on specific surface orientations.
APPLIED SURFACE SCIENCE
(2022)
Article
Chemistry, Multidisciplinary
Debabrata Das, Guillermo Gutierrez, C. V. Ramana
Summary: Using Raman scattering analyses, this study investigates the effect of Sn incorporation on the crystal structure, chemical bonding, and phase formation of Ga2O3 compounds. The results show that Sn-induced changes in chemical bonding and phase segregation are significant. The study also reveals the evolution of Sn-O bonds with increasing Sn concentration.
Article
Physics, Applied
Qian Li, Bang-Deng Du, Jian-Ye Gao, Jing Liu
Summary: This article proposes a new method that could significantly alleviate the complexity of the conventional doping process for semiconductors and achieve a high degree of control over the results by selectively enriching liquid metal interfaces and harvesting doped metal oxide semiconductor layers. The method provides an opportunity for the cost-effective creation of semiconductor films with controlled metal dopants, which is of great significance for synthesis and manufacturing routes in the electronics industry.
APPLIED PHYSICS REVIEWS
(2023)
Article
Materials Science, Multidisciplinary
Xuefen Cai, Fernando P. Sabino, Anderson Janotti, Su-Huai Wei
Summary: This study proposes efficient p-type doping in transparent oxides by adding a small amount of Bi2O3 into Ga2O3 to form dilute (BixGa1-x)(2)O-3 alloys. The addition of Bi raises the intermediate valence band energy, facilitating p-type doping, with commonly expected shallow acceptors showing deeper levels in the alloy. This understanding provides insights into doping semiconductor materials with a strongly correlated band edge state.
Article
Crystallography
Minglei Tang, Guodong Wang, Songhao Wu, Yang Xiang
Summary: Ultra-long Si-doped beta-Ga2O3 nanowires were prepared on annealed Al2O3-film/Si substrate by low-pressure chemical vapor deposition (LPCVD) with Au as catalyst. The nanowires have a length over 300 μm and diameters ranging from about 30 nm to about 100 nm in one-dimensional structures. Their crystal quality is good with (201) orientation confirmed by transmission electron microscopy and X-ray diffraction analysis. The nanowires exhibit three obvious blue luminescence peaks and good conductivity. A metal-semiconductor-metal device made with Ti/Au electrode shows a device current of 200 pA at a bias voltage of 3 V. The results demonstrate the direct growth of ultra-long Si-doped beta-Ga2O3 nanowires on Al2O3-film/Si substrates, which have a high length-diameter ratio and good electrical properties. A possible Si doping mechanism is also proposed.
Article
Engineering, Electrical & Electronic
Shiyu Du, Naisen Yu, Yunfeng Wu, Xiang Lin, Benkang Liu, Haiou Li
Summary: CuO/beta-Ga2O3 hybrid structures with enhanced and broadened light response from near-ultraviolet to visible light were successfully synthesized by a multi-cycle dipping and annealing process method. This novel synthetic pathway provides new possibilities for photodetection applications by integrating oxide heterojunctions.
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2022)
Article
Chemistry, Multidisciplinary
Penghui Li, Linpeng Dong, Chong Li, Bin Lu, Chen Yang, Bo Peng, Wei Wang, Yuanhao Miao, Weiguo Liu
Summary: In this study, the influence of indium doping on the exfoliation efficiency, stability, and structural and electronic properties of ML Ga2O3 is systematically investigated. The results show that indium doping can reduce the exfoliation energy of ML Ga2O3 to a similar level as typical van der Waals 2D materials and maintain excellent stability even at high doping concentrations. Additionally, indium doping can modify the bandgap of ML Ga2O3, improve the electron mobility, and significantly decrease the hole mobility. The simulation of MOSFETs based on indium-doped ML Ga2O3 demonstrates enhanced device performance and potential for sub-5 nm applications.
Article
Biochemistry & Molecular Biology
Siddhartha Banerjee, Divya Baghel, Ana Pacheco de Oliveira, Ayanjeet Ghosh
Summary: This study used nanoscale AFM-IR spectroscopy to investigate the structure of Aβ oligomers and fibrils. It found that the main effect of beta-carotene is not to inhibit fibril formation, but to alter the secondary structure of the fibrils and promote fibrils that lack the characteristic ordered beta structure.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2023)
Article
Chemistry, Physical
Huijuan Wu, Suiting Ning, Xiangbin Chen, Tian Yu, Tingdong Zhang, Xiang Qu, Ning Qi, Zhiquan Chen
Summary: Multiple strategies were employed to suppress the lattice thermal conductivity in beta-Ga2O3, including the introduction of point defects, grain boundaries, secondary phases, and pores. As a result, the as-sintered beta-Ga2O3 exhibited an extremely low thermal conductivity, attributed to the presence of micro-pores, vacancies, and a high porosity.
ACS APPLIED ENERGY MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
Yi Lu, Shibin Krishna, Che-Hao Liao, Ziqiang Yang, Mritunjay Kumar, Zhiyuan Liu, Xiao Tang, Na Xiao, Mohamed Ben Hassine, Sigurdur T. Thoroddsen, Xiaohang Li
Summary: This article introduces a method for transferring Ga2O3 thin film to arbitrary flexible and adhesive tape, enabling vertical and flexible configurations of electronic devices. Vertical photodetectors fabricated using this method demonstrate good optoelectronic performance.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Materials Science, Multidisciplinary
Ymir K. Frodason, Joel B. Varley, Klaus Magnus H. Johansen, Lasse Vines, Chris G. Van de Walle
Summary: Pathways and energy barriers for the migration of Ga vacancies (VGa) and Ga interstitials (Gai) in-Ga2O3 have been studied using hybrid functional calculations and the nudged elastic band method. A mechanism for the transformation of VGa between different split configurations has been described. The overall migration barriers for VGa and Gai in different crystal directions have been determined. The results provide insights into the thermally activated recovery processes in irradiated material.
Article
Physics, Applied
Naxin Zhu, Bowen Wang, Kaichuang Ma, Xiangyi Xue, Jie Su
Summary: The structural and electronic properties of (ScxGa1-x)(2)O-3 alloys were investigated. It was found that (ScxGa1-x)(2)O-3 alloys have more negative formation enthalpies compared to (AlxGa1-x)(2)O-3 alloys, and the increments in positive formation enthalpies of monoclinic (ScxGa1-x)(2)O-3 alloys are different from (AlxGa1-x)(2)O-3 alloys. Compressive strain is observed when (ScxGa1-x)(2)O-3 alloys are grown on Ga2O3 substrate. The bandgaps range from 4.78 to 5.44 eV for monoclinic (ScxGa1-x)(2)O-3, and from 5.17 to 6.10 eV for hexagonal (ScxGa1-x)(2)O-3. Ga2O3/(ScxGa1-x)(2)O-3 heterojunctions maintain type-II band alignments, and the conduction and valence band offsets can be significantly and negligibly enlarged by increasing Sc concentration, respectively. (ScxGa1-x)(2)O-3 alloys can serve as an electron blocking layer for Ga2O3 devices, thus alleviating parasitic conduction issues in field effect transistors.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Ying-Li Shi, Dong Huang, Francis Chi-Chung Ling, Qi-Sheng Tian, Liang-Sheng Liao, Matthew R. Phillips, Cuong Ton-That
Summary: Pulsed laser deposition was used to fabricate as-grown amorphous and post-growth annealed crystalline beta-Ga2O3 films. The films annealed at temperatures above 600 degrees C exhibited a pure monolithic phase with a large bandgap. The thermally activated donor ionization and dielectric relaxation were investigated in these films, revealing the presence of donor levels and small polaron tunneling relaxation in the as-grown amorphous Ga2O3 film but not in the monolithic beta-Ga2O3 film.
APPLIED PHYSICS LETTERS
(2022)
Article
Nanoscience & Nanotechnology
Luke A. M. Lyle, Tyson C. Back, Cynthia T. Bowers, Andrew J. Green, Kelson D. Chabak, Donald L. Dorsey, Eric R. Heller, Lisa M. Porter
Summary: Chemical and electrical measurements of Ti/(010) beta-Ga2O3 and Ti/(001) beta-Ga2O3 interfaces were conducted with XPS, J-V, and C-V measurements as a function of annealing temperature. The results show that the reactivity of Ti on the beta-Ga2O3 surface strongly affects the electrical performance and stability of Ti/beta-Ga2O3 ohmic contacts at elevated temperatures. The oxidized Ti amount increased with annealing temperature, and the Schottky barrier height had variations with temperature changes.
Article
Physics, Applied
Takayoshi Oshima, Yuji Kato, Eiichi Kobayashi, Kazutoshi Takahashi
JAPANESE JOURNAL OF APPLIED PHYSICS
(2018)
Article
Physics, Applied
Hironori Okumura, Yuji Kato, Takayoshi Oshima, Tomas Palacios
JAPANESE JOURNAL OF APPLIED PHYSICS
(2019)
Article
Physics, Applied
Yuji Kato, Masataka Imura, Yoshiko Nakayama, Masaki Takeguchi, Takayoshi Oshima
APPLIED PHYSICS EXPRESS
(2019)
Article
Physics, Applied
Takayoshi Oshima, Yuji Kato, Eisuke Magome, Eiichi Kobayashi, Kazutoshi Takahashi
JAPANESE JOURNAL OF APPLIED PHYSICS
(2019)
Article
Engineering, Electrical & Electronic
Toshiyuki Oishi, Kosuke Urata, Makoto Hashikawa, Kosuke Ajiro, Takayoshi Oshima
IEEE ELECTRON DEVICE LETTERS
(2019)
Article
Physics, Applied
Yuichi Oshima, Katsuaki Kawara, Takayoshi Oshima, Mitsuru Okigawa, Takashi Shinohe
JAPANESE JOURNAL OF APPLIED PHYSICS
(2020)
Article
Engineering, Electrical & Electronic
Yuichi Oshima, Katsuaki Kawara, Takayoshi Oshima, Mitsuru Okigawa, Takashi Shinohe
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2020)
Article
Physics, Applied
Katsuaki Kawara, Takayoshi Oshima, Mitsuru Okigawa, Takashi Shinohe
APPLIED PHYSICS EXPRESS
(2020)
Article
Physics, Applied
Yuichi Oshima, Katsuaki Kawara, Takayoshi Oshima, Takashi Shinohe
JAPANESE JOURNAL OF APPLIED PHYSICS
(2020)
Article
Chemistry, Multidisciplinary
Laura E. Ratcliff, Takayoshi Oshima, Felix Nippert, Benjamin M. Janzen, Elias Kluth, Rudiger Goldhahn, Martin Feneberg, Piero Mazzolini, Oliver Bierwagen, Charlotte Wouters, Musbah Nofal, Martin Albrecht, Jack E. N. Swallow, Leanne A. H. Jones, Pardeep K. Thakur, Tien-Lin Lee, Curran Kalha, Christoph Schlueter, Tim D. Veal, Joel B. Varley, Markus R. Wagner, Anna Regoutz
Summary: Ga2O3 and its polymorphs have great potential for electronic structure engineering. In this study, a robust atomistic model of gamma-Ga2O3 is developed using density functional theory and machine-learning approach, which is validated by experimental results. This work is of significant importance for understanding the electronic structure of complex, disordered oxides.
ADVANCED MATERIALS
(2022)
Article
Physics, Applied
Takayoshi Oshima, Yuichi Oshima
Summary: Selective area growth of beta-Ga2O3 was demonstrated by HCl-based halide vapor phase epitaxy on SiO2-masked (001) and (010) beta-Ga2O3 substrates. High-aspect-ratio structures with (100) sidewall facets were observed for stripe windows along [010] and [001] directions on the respective substrates. These structures can be applied to trenches and fins for beta-Ga2O3-based power devices.
APPLIED PHYSICS EXPRESS
(2022)
Article
Physics, Applied
Takayoshi Oshima
Summary: In this study, a patterned metal on a beta-Ga2O3 substrate surface was used as an embedded photomask to demonstrate the applicability of backside-exposure lithography to beta-Ga2O3 substrates. Self-aligned photoresist patterning, lift-off, and etching processes were demonstrated for an AZ5214E photoresist in both the positive and negative processing modes. The findings suggest that backside-exposure photolithography is a promising fabrication approach for future beta-Ga2O3-based devices.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Hitoshi Takane, Takayoshi Oshima, Katsuhisa Tanaka, Kentaro Kaneko
Summary: Selective-area growth of r-SnO2 was achieved on a SiO2-masked r-TiO2 (110) substrate. The heteroepitaxy process led to the growth of islands with {100}-, {110}-, and {011}-faceted sidewalls, which matched the equilibrium shape of the rutile structure. Coalescence of the islands formed a flat (110) top surface on the striped window, followed by lateral overgrowth. Cross-sectional transmission-electron-microscopy observation revealed that misfit dislocations propagated perpendicular to the facet planes due to the image force effect, and the dislocation density decreased significantly in the wing regions.
APPLIED PHYSICS EXPRESS
(2023)
Article
Physics, Applied
Takayoshi Oshima, Yuichi Oshima
Summary: We have demonstrated the effectiveness of plasma-free HCl gas etching for fabricating high-aspect-ratio fins/trenches on a SiO2-masked (010) beta-Ga2O3 substrate. The etching process resulted in the formation of holes or trenches with etching-resistant (100)- and ((1) over bar 01)-faceted sidewalls. By etching in the striped windows along [001], we achieved fins and trenches with flat (100)-faceted vertical sidewalls and slightly rough {310}-faceted inclined bottom corners. The vertical-to-horizontal etching ratio was as high as about 11-14. Our findings suggest that HCl etching is a promising method for such fabrication without plasma damage.
APPLIED PHYSICS EXPRESS
(2023)
Article
Physics, Applied
Takayoshi Oshima, Yuichi Oshima
Summary: In this study, SiO2-masked (001) beta-Ga2O3 substrates were dry etched in HCl gas flow at a high temperature without plasma excitation. The etching selectively formed holes or trenches with inner sidewalls of (100) and/or {310} facets, which are planes of lowest surface energy density and oxygen-close-packed slip planes, respectively. The (100) faceted sidewalls were flat and close to the substrate surface normal. This dry etching method shows promise for fabricating plasma-damage-free trenches and fins for beta-Ga2O3-based power devices.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Physical
Qi-Wen Chen, Ze-Qing Guo, Jian-Ping Zhou
Summary: Multifunctional continuous solid solutions NFMTO-x were successfully synthesized via a one-step hydrothermal method by controlling the ratio of Mg and Fe. The NFMTO-x materials exhibited enhanced visible light response, effective adsorption and photocatalytic degradation of organic pollutants, CO2 methanation capability, and easy recyclability due to their magnetic properties. This research provides a significant multifunctional material for water purification.
APPLIED SURFACE SCIENCE
(2024)
Review
Chemistry, Physical
George E. Stan, Maziar Montazerian, Adam Shearer, Bryan W. Stuart, Francesco Baino, John C. Mauro, Jose M. F. Ferreira
Summary: Bioactive glasses have the ability to form strong bonds with tissues and release therapeutic ions. However, their biomechanical compatibility limits their use in load-bearing applications. The use of magnetron sputtering technology to fabricate BG coatings shows promise in improving their efficacy and potential for application.
APPLIED SURFACE SCIENCE
(2024)
Article
Chemistry, Physical
Zhaoxuan Wang, Zhicheng Yan, Zhigang Qi, Yu Feng, Qi Chen, Ziqi Song, Meng Huang, Peng Jia, Ki Buem Kim, Weimin Wang
Summary: The corrosion behavior of Fe-60 and Fe-83 ribbons in 0.6 M NaCl was studied. Fe-60 exhibited a local corrosion mode and formed a stable passivation film with higher corrosion resistance, while Fe-83 showed a combination of local and global corrosion modes and had lower corrosion resistance. Controlling the precipitation of nanocrystalline phases and increasing the POx content in the passivation film significantly improved the corrosion resistance of Fe-based glassy alloys.
APPLIED SURFACE SCIENCE
(2024)
Article
Chemistry, Physical
Hao-Kai Peng, Sheng-Yen Zheng, Wei-Ning Kao, Ting-Chieh Lai, Kai-Sheun Lee, Yung- Hsien Wu
Summary: This study investigates the effects of high energy/fluence proton radiation on the performance of HfZrOx-based FeFETs memory with different Zr content. The results show that the characteristics of FeFETs are influenced by proton radiation, and the extent of the influence depends on the Zr content. FeFETs with 50% Zr content exhibit minimal changes in memory window and demonstrate good endurance and retention performance.
APPLIED SURFACE SCIENCE
(2024)
Article
Chemistry, Physical
Zongyi Yue, Guangyi Wang, Zengguang Huang, Sihua Zhong
Summary: In this study, AZO and ITO films were successfully tuned as excellent passivation layers for c-Si surfaces, achieving effective minority carrier lifetime and outstanding optical properties through the optimization of annealing temperature and interfacial silicon oxide.
APPLIED SURFACE SCIENCE
(2024)
Article
Chemistry, Physical
Martin Hruska, Jan Kejzlar, Jaroslav Otta, Premysl Fitl, Michal Novotny, Jakub Cizek, Oksana Melikhova, Matej Micusik, Peter Machata, Martin Vrnata
Summary: This paper presents a detailed study on the hydrogen sensing capabilities of highly nanoporous black gold films. The films exhibit fast response and recovery times at low temperatures. Different levels of nanoporosity were prepared and tested to investigate the sensing properties, and it was found that nanoporous black gold is suitable for hydrogen sensing. The sensitivity of the film depends on its nanoporosity.
APPLIED SURFACE SCIENCE
(2024)
Article
Chemistry, Physical
Yupu Wang, Gaofeng Teng, Chun To Yiu, Junyi Zhu
Summary: In the study of BM-SCO and HSCO thin films, it was found that H vacancies tend to prefer sites near the external surface or oxygen vacancy channels (OVCs), while H interstitials prefer sites of oxygen on a layer that contains six-fold coordinated Co. These findings not only enrich the understanding of complex surface phenomena of defect formation but also provide an explanation for the reversibility during phase transformation.
APPLIED SURFACE SCIENCE
(2024)
Article
Chemistry, Physical
Jiafeng Lu, Linping Teng, Qinxiao Zhai, Chunhua Wang, Matthieu Lancry, Ye Dai, Xianglong Zeng
Summary: In this study, we achieved full control of fiber nanograting orientation by manipulating laser polarization, and tailored space variant fiber nanogratings, which expanded the diversity in fiber nanograting engineering.
APPLIED SURFACE SCIENCE
(2024)
Article
Chemistry, Physical
Yibo Liu, Yujie Tao, Yue Liu, Qi Sun, Qinrong Lin, Kexin Kang, Qinghua Zhang, Qingjie Sun
Summary: This study investigates the wettability of the Ti-Cu-Fe multi-metal system, specifically the wetting behaviors of CuSi3 droplets on TC4 and 304SS plates. The results show that the CO2 + Ar gas atmosphere significantly affects interfacial mass transfer, thus influencing the wettability of the systems.
APPLIED SURFACE SCIENCE
(2024)
Article
Chemistry, Physical
Jimei Liu, Fei Wang, Rong Guo, Yuqi Liu, Mengyu Zhang, Jaka Sunarso, Dong Liu
Summary: This study developed Co/MXene composites with anti-corrosion properties by varying the cobalt content. These composites exhibited remarkable electromagnetic absorption performance and high resistance to corrosion under various corrosive conditions. The study also revealed the mechanism of electron transfer from cobalt to MXene and the electromagnetic dissipation behavior originated from polarization loss alone.
APPLIED SURFACE SCIENCE
(2024)
Article
Chemistry, Physical
Moujie Huang, Yongsong Ma, Jingbo Yang, Lingyun Xu, Hangqi Yang, Miao Wang, Xin Ma, Xin Xia, Junhao Yang, Deli Wang, Chuang Peng
Summary: Strong metal-support interactions (SMSIs) are important for enhancing catalytic activities and stability in thermal catalysis. This study demonstrates a method to create SMSIs in electrocatalysis using carbon nanotubes and Ru nanoparticles, resulting in excellent catalytic activity and stability.
APPLIED SURFACE SCIENCE
(2024)
Article
Chemistry, Physical
Ravi Trivedi, Brinti Mondal, Nandini Garg, Brahmananda Chakraborty
Summary: This study explores the potential of biphenylene as a nanocarrier for the delivery of the anticancer drug cisplatin. It is found that biphenylene offers physical stability, rapid release rate, solubility, and bio-compatibilities compared to other nanocarriers. The adsorption of cisplatin on the surface of biphenylene involves charge transfer from cisplatin to biphenylene. The drug is shown to be released at body temperature in an acidic environment. Biphenylene also exhibits excellent cytotoxicity activity and cellular uptake of the drug. Overall, biphenylene shows promise as a potential nanocarrier for cisplatin delivery.
APPLIED SURFACE SCIENCE
(2024)
Article
Chemistry, Physical
Hyun Jeong, Hyeong Chan Suh, Ga Hyun Cho, Rafael Salas-Montiel, Hayoung Ko, Ki Kang Kim, Mun Seok Jeong
Summary: In this study, a potential platform to enhance Raman scattering and increase the number of observable Raman modes in monolayer transition metal dichalcogenides (TMDs) was proposed. The platform consisted of large-scale arrays of gold micropillars (MPs), which were able to enhance the Raman intensity of TMDs and make difficult-to-detect Raman modes observable. The platform showed great industrial advantages and wide applicability due to its low cost, simple process, large controllable area, and short process time.
APPLIED SURFACE SCIENCE
(2024)
Article
Chemistry, Physical
Yasir Abbas, Shafqat Ali, Sajjad Ali, Waqar Azeem, Zareen Zuhra, Haoliang Wang, Mohamed Bououdina, Zhenzhong Sun
Summary: In this study, FeOx@SPNO-C core-shell nanospheres as a catalyst for degradation of sulfamethoxazole (SMX) were successfully synthesized. The synergistic interaction between FeOx and SPNO-C, high carbon charge density, and the presence of C = O groups and N/Fe-Nx sites were found to be key factors for the enhanced degradation of SMX.
APPLIED SURFACE SCIENCE
(2024)
Article
Chemistry, Physical
Qiaoting Yang, Yuxiao Gong, Yan Qian, Zhou-Qing Xiao, Serge Cosnier, Xue-Ji Zhang, Robert S. Marks, Dan Shan
Summary: This study proposes a hierarchical confinement strategy to design Prussian blue nanoparticles (PB NPs) with satisfactory electrocatalytic ability and stability. The catalytic synthesis of PB NPs is achieved through a hydrothermal process, and the as-prepared PB@NH2MIL exhibits efficient electronic transmission and enhanced electrocatalytic properties.
APPLIED SURFACE SCIENCE
(2024)