A high-speed, high-voltage EPI base GTO

The development and performance of an 8A/600V gate turn-off device is discussed. The structure is built on high-resistivity n-type material using a uniformly doped, gated p-base. A test array of 8 devices was simultaneously processed on the same wafer; all geometries had approximately equal cathode areas. The cathode width, however, was varied from 2 mils to 20 mils. Switching performance was investigated. Turn-on time was relatively independent of the particular geometry while storage time and fall time decreased with decreasing cathode-finger width. Gate trigger current and forward voltage drop increased with narrowing cathode width, however. Four-hundred nanoseconds rise time and 140 nanoseconds fall time were observed for IT= 8 amperes and VD= 200 volts at Tj= 125°C with the 4-mil-wide cathode geometry.