Gallium Nitride Nanostructured Power Semiconductor Devices

摘要

Gallium nitride (GaN) has emerged as a promising material for development of power semiconductor devices owing to its superior material characteristics. Fabricated GaN power devices have outperformed its silicon (Si) counterpart with low conduction and switching losses and holds the key to extremely low-loss and high-efficiency power delivery circuits of the future. However, GaN power devices have been plagued with several inherent drawbacks preventing a ubiquitous adoption of GaN as the material of choice for power switches. The most critical trade-off has been the choice of substrate for the growth of GaN epitaxy: a high performance, high-cost native substrate or a low-cost, non-native substrate with reliability issues. For GaN to thrive as a superior successor to Si, a low cost, high performance epitaxy with improved reliability is expected moving forward.;A novel nanostructured approach to GaN power devices is proposed in this dissertation. The nano-GaN power devices theoretically have the potential to bypass the reliability concerns associated with a non-native substrate but still deliver comparable performance. A comprehensive model is proposed for TCAD modeling of bulk GaN power devices to accurately model the nano-GaN devices. Through extensive modeling and simulations, design guidelines for Schottky barrier diodes and field effect transistors based on the nano-GaN concept is laid out to extract the best performance out of this architecture. Dielectric and semiconductor interaction is also exploited to push these devices to perform beyond the unipolar material limit of GaN. The simulated and fabricated nano-GaN power devices show the potential to deliver equivalent or superior performance to present state of the art GaN devices but with improved reliability, ruggedness and low cost.