Optimum semiconductors for power field effect transistors

The optimization of semiconductor material properties for high voltage field effect transistors is discussed. The on-resistance of these devices is shown to be inversely proportional to the carrier mobility and inversely proportional to the cube of the energy band gap. Based upon this, the on-resistance of GaAs FETs is predicted to be at least twelve times smaller than that of present silicon FETs. Comparison of the projected GaAs FET power switching performance with competing silicon devices (MOSFETs, FCTs, GTOs, and bipolar transistors) indicates that the GaAs FET will have better switching efficiency at all operating frequencies for devices designed with breakdown voltages ranging from 200 to 1000 volts.