【Member Papers】Professor Yang Weifeng's team at Xiamen University has made important progress in the research of fourth-generation semiconductor Gallium Oxide material epitaxy and deep ultraviolet detection applications

      Recently, Professor Yang Weifeng's team in the College of Electronic Science and Technology has made important progress in the epitaxy growth technology of the fourth generation semiconductor Gallium Oxide (β-Ga₂O₃) and the preparation of Solar-blind photodetector. Related research results have been published in a number of IEEE academic Journals in the field of microelectronics device manufacturing (IEEE Transactions on Electron Devices, IEEE Sensor Journals, IEEE Photonics Technology Letters), these research results provide important support for the large area growth of β-Ga₂O₃ heteroepitaxial films and high performance device applications.

FIG. 1 MBE heteroepitaxy growth mechanism and material characterization analysis of Gallium Oxide materials.(see Sensor IEEE Journals DOI 10.1109 / JSEN. 2024.3373252)

      β-Ga₂O₃ material has been widely concerned in the field of Solar-blind photodetectors due to its intrinsic Solar-blind light absorption (254 nm), simple binary composition, adjustable band gap and simple preparation process. In terms of β-Ga₂O₃ film growth, the research team used molecular beam epitaxy technology (MBE) to achieve high quality, low defect density epitaxy film growth. By changing the reactant precursor and precisely controlling the growth parameters, the β-Ga₂O₃ epitaxy films have successfully achieved uniform growth and excellent crystal quality, which has strongly promoted the development of high-quality heteroepitaxy of β-Ga₂O₃ films. At the same time, the research team also explored the growth mechanism of β-Ga₂O₃ films during the epitaxy growth of MBE in detail, revealed the differences in nucleation and growth, and established the corresponding epitaxy growth mechanism model. The research results are shown in Figure 1.

Figure 2 Schematic diagram of CuCrO₂/β-Ga₂O₃ p-n heterojunction photodetector structure, performance and energy band.(See IEEE Transactions on Electron Devices DOI 10.1109/TED.2024.3373382 for details.)

      In the preparation of β-Ga₂O₃ Solar-blind photodetector, The CuCrO₂/β-Ga₂O₃ p-n heterojunction self-powered Solar-blind photodetector prepared by the research team based on the Type II band structure has a low dark current of 6.5 pA, a high light-to-dark current ratio of 5.7×10⁴, a high responsiveness of 50 mA/W, a high detectivity of 3.7×10¹² Jones, and a high external quantum efficiency of 24.6%. Which is superior to most reported β-Ga₂O₃ based heterojunction photodetectors. The results of the research are shown in Figure 2. In addition, based on the growth mechanism of MBE heteroepitaxy β-Ga₂O₃, combined with the semiconductor photoelectric response principle, the performance index of heteroepitaxy β-Ga₂O₃ thin film Solar-blind photodetector was investigated. The metal-semiconductive-metal Solar-blind photodetector prepared by the research team using ozone as A precatalyst exhibits a dark current of 7.5 pA, a light-to-dark current ratio of 1.31×10⁷, a specific detection rate of 1.31×10¹⁵ Jones, and a light responsiveness of 53 A/W, showing excellent detection performance for Solar-blind ultraviolet light. At the same time, in view of the shortcomings of the large dark current of the epitaxial thin film photodetector, the research team introduced a passivation layer at the gold half interface to improve the device performance: By using the AlN/β-Ga₂O₃ interface engineering to control the carrier transport at the gold half interface, the fabricated metal-insulator-semiconduction-insulator-metal (MISIM) solar-blind photodetector has achieved the simultaneous optimization of responsiveness and response speed. The photodevice with 3 nm AlN layer exhibits a responsiveness of 482 A/W, a specific detectiveness of 2.48×10¹⁵ Jones, and a fast fall time of 0.10 s. The results of the research are shown in Figure 3.

FIG. 3 Photodetection performance and energy band maps of Gallium Oxide MSM and MISIM Solar-blind deep ultraviolet photodetectors.(for details, please see the IEEE Sensor Journals DOI 10.1109 / JSEN. 2024.3373252, IEEE Photonics Technology Letters, 36, 593-596 (2024))

      The research progress of the research team in β-Ga₂O₃ materials and devices provides a technical reference for the application and development of ultra-wide band gap semiconductors in the field of Solar-blind deep ultraviolet detectors, promotes the innovative development of ultra-wide band gap semiconductor-based optoelectronics technology, and opens up a research approach for the construction of low-noise, high-light response optoelectronic devices.

      The first signed unit of the three papers are all Xiamen University. The first authors are Tian Chengyi, a PhD student in 2021, Zhang Chuanlun, a master student in 2021 (tied for the first place), Lin Jialong, a master student in 2022, Zhang Chuanlun, a master student in 2021, and the only corresponding authors are Professor Yang Weifeng of our college. The research group was supported by the National Natural Science Foundation of China, Fujian Province's "Minjiang Scholars" Project, Xiamen's "Double Hundred Talents Plan" and Fujian Province's "* Hundred Talents Plan".