New Materials Beyond Silicon for Power Devices

Abstract

At present, semiconductor based power electronic systems rely extensively upon silicon power devices. The introduction of Metal Oxide Silicon (MOS) technology to power devices in the 1970s and 1980s has resulted in a displacement of the bipolar power transistors with power MOS Field Effect Transistors (MOSFET′s) and Insulated Gate Bipolar Transistors (IGBT′s). This change is motivated by the simplification in the gate control circuit due to the high input impedance of these MOS-gated power devices. In the 1990s, the Gate-Turn-Off Thyristor (GTO) is also expected to be challenged by the development of MOS-gated thyristors.

Looking into the future on a longer time scale, it is anticipated that the silicon devices could be replaced by devices based upon other semiconductor materials. Recent analysis has shown that the specific on-resistance of power MOSFETs can be reduced by one order of magnitude using Gallium Arsenide, by two orders of magnitude using Silicon Carbide, and three orders of magnitude using Semiconducting Diamond. It has also been shown that a 5000 V Silicon Carbide based MOSFET could have a forward drop lower than that of a 5000 V Silicon GTO. which indicates the possibility to replace the entire spectrum of Silicon devices with Silicon Carbide devices. This paper will describe the reasons for these conclusions and outline the technological challenges that must be overcome to fabricate these devices.