ION-IMPLANTED NORMALLY-OFF GAAS BIPOLAR-MODE FET (BMFET) FOR APPLICATION IN A WIDE TEMPERATURE-RANGE

First results of a normally-off GaAs bipolar-mode field effect transis tor (BMFET) produced by ion implantation into an epitaxial n(+)-n(-)-n (+) material are presented. The devices show extreme temperature stabi lity of drain current, current gain, on-resistance and switching times up to 350 degrees C and were still operational at 450 degrees C. Chan ges in drain current can be limited to -2%/100 K and small-signal curr ent gain varies by as little as -4%/100 K in the whole temperature ran ge. Although they have characteristics like bipolar transistors, BMFET s have the great advantage of a decrease in drain current and current gain with increasing temperature so that self-heating does not occur u p to a limiting temperature. The influence of the number of source fin gers is examined. In addition to the DC properties, switching behaviou r is presented in a wide temperature range and shows almost no degrada tion.