High Power Switching Devices: Past, Present and Future

Switching devices are key components in any power electronic circuit or system as they control and limit the flow of power from the source to the load. Their power level requirements (current & voltage) and switching frequency are continually increasing in the power electronic industry, and this demands larger and faster switching devices. This paper will focus on the development of high power switching devices and will present an up to date perspective of switching device technology and materials. The most important material has been and still is silicon (Si) for solid-state semiconductor devices. It dominates the world market at present, particularly in its crystalline form. However, silicon power device operation is generally limited to relatively low frequency and temperature. Silicon Carbide, Gallium Nitride and Diamond offer the potential to overcome the frequency, temperature and power management limitations of silicon. A large number of new concepts and materials are still in the research stage. At present, Silicon Carbide is considered to have the best trade-off between material properties and commercial maturity. Multilayer Silicon Carbide (SiC) power semiconductor devices being in development are promising devices for the near future, but long term reliability, crystal degradation and forward voltage drift problems need to be solved before commercialisation.