Design and Optimization of GaN-Based Power Semiconductor Transistors

Gallium Nitride, a wide bandgap semiconductor, is a robust material with applications in high-power transistors and power amplifiers. However, processing technology is still maturing and transistors performance are far from theoretical limits. We investigate several design aspects of the heterojunction transistor including ohmic contact, gate insulation and high off-state breakdown. We discuss ohmic contact formation approaches for low contact resistance (Rc) and low temperature processing and achieve Rc less than 0.2 Ω∙mm. For the transistor gate insulation in the Metal-Insulator-Semiconductor Heterojunction, we study many high-κ dielectrics, deposited by Atomic Layer Deposition, using both TiO2 and HfO2 variations. We also discuss methods towards evaluating interface trap defects at the insulator/GaN interface. Lastly, we cover one method towards improving off-state breakdown voltage for an InAlN/GaN transistor. Various electrical characterization methods are discussed such as pulsed and DC Current-Voltage and Capacitance-Voltage measurements.