Silicon carbide power MOSFETs are under development to replace silicon IGBTs for high-efficiency power conversion applications. Commercial SiC power MOSFETs have a short-circuit (SC) capability inferior to those of Si IGBTs, thus constraining their widespread use. Gate drive voltage levels for SiC power MOSFETs can be reduced to increase SC capability but this results in a large increase in on-resistance. This paper presents a new method, with a series-connected Gate-Source-Shorted (GSS) Si Depletion-Mode (DM) MOSFET, to enhance the short-circuit capability of SiC power MOSFETs and compares its performance with the gate drive level adjustment approach for the first time. The SC capability of a 1.2kV SiC power MOSFET operating at 800V with a gate bias of 20V is demonstrated to improve from 4.8μ s to beyond 7.5μ s with only 17% increase in on-resistance using the new approach, whereas the gate drive level adjustment method produces a similar improvement in SC capability with a 66% increase in on-resistance. Measured static and dynamic characteristics demonstrate less than 20% increase in switching power loss using the new method. The new method also provides a voltage sensing node at the drain of the GSS Si DM MOSFET for detection of SC events, which is not available in the case of the conventional single SiC MOSFET.

Power electronic systems have benefited greatly during the past ten years from the revolutionary advances that have occurred in power discrete devices. The introduction of power metal-oxide-semiconductor field-effect transistors (MOSFETs) in the 1970s and the insulated gate bipolar transistors (IGBTs) in the 1980s enabled design of very compact high-efficiency systems due to the greatly enhanced power gain resulting from the high input impedance of these structures. Recently, significant improvements in the performance of silicon-power MOSFETs has been achieved by using innovative vertical structures with charge coupled regions. Meanwhile, silicon IGBTs continue to dominate the medium- and high-voltage application space sue to scaling of their voltage ratings and refinements to their gate structure achieved by using very large scale integration (VLSI) technology and trench gate regions. Research on a variety of MOS-gated thyristors has also been conducted, resulting in some promising improvements in the tradeoff between on-state power loss, switching power loss, and the safe-operating-area. Concurrent improvements in power rectifiers have been achieved at low-voltage ratings using Schottky rectifier structures containing trenches and at high-voltage ratings using structures that combine junction and Schottky barrier contacts. On the longer term, silicon carbide Schottky rectifiers and power MOSFETs offer at least another tenfold improvement in performance. Although the projected performance enhancements have been experimentally demonstrated, the defect density and cost of the starting material are determining the pace of commercialization of this technology at present.

Advances in power semiconductor technology are the driving force for enhancement of the performance of variable-frequency motor drives. The development of power semiconductor devices with MOS-gate structures has enabled the control of large amounts of energy with very little input power. An equally important advancement has taken place in the development of improved rectifiers with reduced losses for high-frequency operation. In addition, the advent of MOS-gated power switches has led to the creation of smart power technology which makes compact systems with built-in diagnostic and protection functions commercially feasible. Although the power semiconductor chips are all made from silicon today, recent analysis has indicated that devices fabricated from silicon carbide have the potential for completely displacing silicon devices in the long range.>

A review of the innovations that have led to the evolution of a power transistor technology based on MOS gate control is provided. This technology offers the advantage of very high input impedance, which allows the control of the devices using low-cost integrated circuits. The physics of operation of the two types of devices in this category, power MOSFETs and power MOS-bipolar devices, are described. Trends in process technology and device ratings are analyzed. Based on the superior performance of these devices, it is projected that they will completely displace the power bipolar transistor in the future.>