||Wright-Patterson AFB, OH 454337542
Wide bandgap power semiconductor devices have shown many benefits for advanced power conversion and distribution systems. The wider bandgap is accompanied by a higher maximum operating temperature and a higher critical field which leads to lower on-resistance, higher power density, and less switching losses. Overall, these factors make for a more efficient and rugged power electronics system. Ultra-wide bandgap semiconductors have the potential to push these benefits even further. For example, ß-Ga2O3, has a reported bandgap of around 4.8 eV and a predicted critical field strength of 8 MV/cm. Gallium oxide can also be grown from a melt, unlike SiC and GaN. Therefore, large, affordable, high quality substrates are predicted in the relatively near future. Large, high-quality substrates also open the possibility for high power density vertical devices. Gallium oxide does have some disadvantages, however. Thermal conductivity is low, electron mobility is modest, and there is no p-type doping. Unipolar devices utilizing field effect gating are still feasible and have been successfully demonstrated. In this topic, we seek to advance device fabrication techniques and device designs that can utilize gallium oxide and/or other ultra-wide bandgap semiconductors for fast-switching, high power density devices for switch-mode power supplies and circuit protection devices. In addition to field-gated devices, we have interest in optically controlled devices for fast switching and electromagnetic interference immunity. This work will involve standard semiconductor fabrication techniques as well as material and device analysis. Experience with finite element analysis and x-ray diffraction are desirable.
Higashiwaki, M., et.al: “State-of-the-art technologies of gallium oxide power devices,” J. Phys. D: Appl. Phys. Vol 50 (2017) 333002
Tsao, J. Y.; et.al: “Ultrawide-Bandgap Semiconductors: Research Opportunities and Challenges,” Adv. Electron. Mater. Vol 4 (2018) 1600501
Pearton, S.J.; et.al: “A review of Ga2O3 materials, processing, and devices,” Appl. Phys. Rev. Vol 5, (2018) 011301
wide bandgap; ultra-wide bandgap; gallium oxide; power semiconductors; vertical transistor; photoconductive; high frequency; EMI immune