Abstract
Recently, GaN-based power devices have received significant attention for high power, high frequency and high temperature applications due to their superior electrical characteristics including low on-resistance, high current density, high switch speed, high critical breakdown electric field, and good thermal stability. With the gradually advanced epitaxy technology, GaN not only can be grown on the large size Si substrate at low price but also may be integrated with CMOS in the future. Therefore, GaN-on-Si substrate is a very promising choice for high power applications. In this thesis, we demonstrated the InAlN/GaN High Electron Mobility Transistors (HEMTs) on a Si substrate with hybrid drain and hybrid source/drain structures. Both structures can achieve higher VBK than conventional HEMTs at the same Ron and meanwhile will not degrade the high frequency characteristics. More importantly, the hybrid source/drain HEMTs have the increased breakdown voltage (VBK) at the same Ron because the hybrid Schottky-ohmic structures can manipulate the electric field distribution and reduce the peak electric field leading to suppression of source-carrier-injection and impact ionization underneath the drain-side gate edge. The VBK of hybrid source/drain HEMTs can be improved up to 120% (from 50 V to 110 V) compared with conventional HEMTs. On the other hand, we also demonstrated the AlGaN/GaN Schottky Barrier Diodes (SBDs) on a Si substrate with Schottky recessed anode by neutral beam etching (NBE) and inductive coupled plasma (ICP). The recessed anode SBDs can effectively reduce Von and simultaneously realize higher VBK than non- recessed anode SBDs at the same Ron no matter which etching method is used (NBE or ICP). Most importantly, due to nearly damage-free etching by NBE technology, the anode-recessed SBDs by NBE achieve a better performance than the SBDs etching by ICP. Finally, the NBE technology compared with conventional SBDs can reduce Von from 1.1 V to 0.55 V with an enhanced VBK up to 369% (from 130 V to 610 V).