Fujia Gallium MBE Gallium Oxide Epitaxial Films Match World-Leading Electrical Performance, Published in Materials Today Physics

Supported by the National Key R&D Program "Research on Large-Size Gallium Oxide Semiconductor Materials and High-Performance Devices" (Project No. 2022YFB3605500), Zhang Hongliang of Xiamen University systematically studied the electrical transport properties of gallium oxide thin films prepared by molecular beam epitaxy (MBE) supplied by Hangzhou Fujia Gallium Technology Co., Ltd. (hereinafter, Fujia Gallium), and compared the results with those of research teams in Japan and the United States. The results show that the electrical performance of the gallium oxide MBE epitaxial wafers grown by Fujia Gallium is on par with the best levels achieved abroad. In addition, in collaboration with the team at the Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, the researchers investigated the Sn-doping activation mechanism and microscopic information on defect states using temperature-dependent electrical transport measurements and high-resolution photoelectron spectroscopy, providing guidance for further optimizing doping strategies and device performance. The related findings were published in the internationally renowned applied physics journal Materials Today Physics (impact factor 10.0).

Gallium oxide is an emerging ultra-wide-bandgap semiconductor material with outstanding properties, including an ultra-wide bandgap, high breakdown voltage and excellent thermal stability. It is a material of choice for next-generation power electronic devices and deep-ultraviolet optoelectronic devices, with potential applications in new energy vehicles, rail transit, smart grids, aerospace, missile early warning and other high-end fields. Gallium oxide is therefore hailed as a "fourth-generation" semiconductor. It has drawn great attention from the semiconductor industry and academia worldwide and is developing rapidly. In August 2022, the United States and Japan successively imposed gallium oxide embargoes on China, underscoring its importance in international strategic competition. The gallium oxide semiconductor industry chain covers such major steps as single-crystal substrates, thin-film epitaxy and device fabrication. Among these, the epitaxial thin film is the critical bottleneck linking the gallium oxide substrate to the device, and its quality determines device performance.To achieve high-performance gallium oxide electronic devices, it is necessary to prepare epitaxial thin films with low defect density and high mobility, and to precisely control their electrical properties.MBE technology enables atomic-layer-level precision control during thin-film growth, yielding films with low defect density and extremely high interface quality. These advantages are of great significance for lateral devices or for building interfacial two-dimensional electron gases to realize high-electron-mobility transistors (HEMT).

Fujia Gallium is one of the earliest organizations in China to work on MBE epitaxy of gallium oxide thin films. Using MBE technology, it successfully grew unintentionally doped (UID) Ga₂O₃ thin films with background carrier concentrations controllable to 1.6×10¹⁶ cm^-3 and room-temperature electron mobility as high as 129 cm²V^-1s^-1. On this basis, by precisely adjusting the temperature of the Sn dopant source K-cell, Ga₂O₃ thin films with different Sn doping concentrations were further prepared, achieving wide-range control of carrier concentration from 1.7×10¹⁷ cm^-3 to 2.8×10¹⁹ cm^-3 (Figure 1a). The electrical performance of the Sn-doped gallium oxide MBE epitaxial thin films is comparable to the best levels achieved with MBE technology by NCT (novel crystal technology) in Japan and the team of Professor James Speck at the University of California, Santa Barbara (UCSB) in the United States (Figure 1b).

Figure 1 (a) Carrier concentration and mobility of Ga₂O₃ thin films obtained at different Sn source temperatures; (b) comparison of the mobility-versus-carrier-concentration relationship of MBE-grown Ga₂O₃ thin films between this work and other reports.

On this basis, the research team combined temperature-dependent transport measurements with internationally advanced synchrotron-based hard X-ray photoelectron spectroscopy (Diamond Light Source, UK) to systematically study the electrical transport properties and electronic structure of the epitaxial thin films. The study revealed the evolution and physical mechanisms of the electrical transport mechanism, defect states, electronic structure and other microscopic information in Sn-doped Ga₂O₃ thin films as a function of Sn doping.

Figure 2 Experimental data and fitting results for the temperature-dependent (a) carrier concentration and (b) mobility of UID Ga₂O₃; experimental data and fitting results for the temperature-dependent (c) carrier concentration and (d) mobility of Sn-doped Ga₂O₃.

The related work was published under the title “Transport and electronic structure properties of MBE grown Sn doped Ga₂O₃ homo-epitaxial films” inMaterials Today Physics 48, 101555 (2024) .

Article link:

Transport and electronic structure properties of MBE grown Sn doped Ga₂O₃ homo-epitaxial films

Materials Today Physics 48, 101555 (2024)

https://www.sciencedirect.com/science/article/pii/S2542529324002311

Hangzhou Fujia Gallium Technology Co., Ltd.

Hangzhou Fujia Gallium Technology Co., Ltd. was founded on December 31, 2019, as the first "hard tech" company established by the Hangzhou Institute of Optics and Fine Mechanics. Guided by its vision of "letting the world use better materials," the company focuses on the industrialization of wide-bandgap gallium oxide semiconductor materials, mainly engaged in the growth of gallium oxide single crystals and the R&D, production and sale of gallium oxide substrates and epitaxial wafers. Its products are primarily used in power devices, microwave and RF, and photodetection.

To date, the company has received numerous honors: it was recognized as a Zhejiang science and technology-based SME in 2022, a national high-tech enterprise in 2023, and in 2024 as a Hangzhou enterprise high-tech R&D center and a Zhejiang "specialized, refined, distinctive and innovative" SME. In the gallium oxide field, it has undertaken one project of the National Development and Reform Commission and one of the Ministry of Industry and Information Technology, and participated in three national and provincial/ministerial-level projects backed by the National Natural Science Foundation of China, Zhejiang Province and Shanghai. It has also been granted 12 international patents (six in the United States and six in Japan) and 40 Chinese patents, secured three trademark registrations for "Fujia Gallium," and obtained two software copyrights (for its "one-click crystal growth" control software).