SiGe/Si HBTs with current gain of negative temperature dependence

In this paper, we analysis the basic principle of SiGe/Si HBTs, design and fabricate power transistors with current gain of negative temperature dependence. The current gain of such transistors decreases from 33 to 20, when the temperature rises from 300 K to 385 K, at the case the quiescent current, I/sub cm/, is 200 mA and V/sub ce/ is 2 V. These power HBTs are to be used in medium power amplifiers.