| Electric energy is essential in industrial and consumer applications. In order to generate, distribute and use electric energy efficiently, power electronic systems are widely used. Modern power electronic systems are based on power semiconductor devices, and the performance of a power electronic system depends largely on the performance of the power semiconductor devices that are used. Power semiconductor devices are required to have high breakdown voltage, low leakage current, low on-resistance/on-state voltage drop, high input impedance and high ruggedness.;In this thesis, power devices with a programmable V TH are demonstrated by using a silicon nitride-based charge trapping gate, which provides an additional flexibility in devices design. It is demonstrated in this thesis that this flexibility can result in significant improvement in device performance. First, an SONOS gate power MOSFET (SG-MOSFET) with heavily doped body region is proposed, demonstrated and characterized. The heavily doped body region results in a much reduced base resistance of the parasitic BJT, and the avalanche energy absorption of the SG-MOSFET at unclamped inductive switching (UIS) is 5.2 times that of the conventional power MOSFET. Second, a planar SG-MOSFET with an ultra-shallow body region is designed, demonstrated and characterized. The ultra-shallow body provides a much reduced parasitic JFET resistance, and the non-optimized R ON·QG product of the device is comparable to that of trench power MOSFETs fabricated using more advanced technologies. Third, threshold voltage (VTH ) stability of the ultra-shallow body SG-MOSFET under hot carrier injection conditions is characterized and discussed. Experimental results indicate that hot electron injection will increase the VTH from 1 V to 2 V in the lifetime of 10 years, while hot hole injection has no significant influence on the VTH stability. Finally, an SNOS gated, normally-off PIN diode (SGNOD) is proposed and experimentally demonstrated. The SGNOD has an extremely low on-state voltage drop of 1.7 V, and the on-state voltage drop is about 0.6 V lower than that of an IGBT, resulting in about 26% reduction in the conduction loss. |
