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. Devices made from SiC, GaN, or other suitable semiconductor capable of enabling switches with low conduction and switching losses with fast switching are desired. This work will involve standard semiconductor fabrication techniques as well as material and device analysis.

Experience with semicondutor device finite element analysis and x-ray diffraction are desirable.

References

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

key words

wide bandgap; ultra-wide bandgap; gallium oxide; power semiconductors; vertical transistor; photoconductive; high frequency; EMI immune; silicon carbide; gallium nitride

Citizenship:  Open to U.S. citizens

Level:  Open to Postdoctoral and Senior applicants

Additional Benefits

Relocation

Awardees who reside more than 50 miles from their host laboratory and remain on tenure for at least six months are eligible for paid relocation to within the vicinity of their host laboratory.

Health insurance

A group health insurance program is available to awardees and their qualifying dependents in the United States.