THERMAL CHARACTERIZATION OF THERMALLY-SHUNTED HETEROJUNCTION BIPOLAR-TRANSISTORS

Heterojunction Bipolar Transistors (HBT's) are potentially useful in a number of microwave applications, but they are severely limited by a current distribution instability caused by electrothermal interaction and the use of a low thermal conductivity substrate. A novel thermal m anagement technique called ''thermal shunting'' has been developed to reduce thermal resistance and junction temperature non-uniformity. The rmal resistance measurements for thermally-shunted devices are present ed. Specific thermal resistance measurements as low as 2.6 x 10(-4) de grees C-cm(2)/W (147 degrees C/W at 0.1 W for a device with a 177 mu m (2) emitter area) have been obtained. Thermal resistance values obtain ed for thermally-shunted HBT's are substantially lower than those repo rted for conventional HBT's.