A detailed study of a MOS-Bipolar power semiconductor known as the IGT or COMFET or GEMFET was undertaken. The major disadvantage of the device was identified as latching and the effect of various factors affecting latching were determined. The experiments performed determined susceptibility to latch under various conditions of temperature, rate of rise of gate-source voltage and rate of fall of drain-source voltage. A 340V, lOA three phase GEMFET bridge inverter using a pulse width modulation scheme to drive a permanent magnet brushless dc motor was successfully fabricated. The simplicity of the gate drive circuit and the low cost of the device make the IGT ideal for motor drive applications. / M.S.