Applied Physics Seminar | Ultra wide bandgap oxide semiconductor materials and devices

Abstract:
The energy bandgap between full and empty electron states is the defining property of a semiconductor. The magnitude of the bandgap determines many important features, such as the semiconductor’s intrinsic resistivity, the electric field and temperature it can sustain before breakdown, its ability to form ohmic contacts, and the optical wavelengths it can absorb or generate. While wide bandgap semiconductors such as silicon carbide and gallium nitride recently have been commercialized in power electronics and ultraviolet/blue photonic devices, the search is now on to identify next generation “ultra wide” bandgap semiconductors. In this seminar, I will describe the current state of the art for two oxide semiconductors that my group studies: gallium oxide and germanium dioxide. I will review the properties of these materials that make them particularly attractive for power electronic devices, methods for synthesis of bulk substrates and thin films, and key electronic properties such as charge transport and doping, dielectric interfaces for MOSFETs and low-resistance ohmic contacts.