Thermal characterization of thermally-shunted heterojunction bipolar transistors

Heterojunction Bipolar Transistors (HBTs) 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 management technique called "thermal shunting" has been developed to reduce thermal resistance and junction temperature non-uniformity. Thermal resistance measurements for thermally-shunted devices are presented. Specific thermal resistance measurements as low as 2.6/spl times/10/sup -4//spl deg/C-cm/sup 2//W (147/spl deg/C/W at 0.1 W for a device with a 177 /spl mu/m/sup 2/ emitter area) have been obtained. Thermal resistance values obtained for thermally-shunted HBTs are substantially lower than those reported for conventional HBTs.

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