Modelling the Effect of Temperature on the Electrical Performance of an HBT Power Transistor

Study of the thermal behavior of power transistors has been a major issue accompanying the development of bipolar technologies. A better understanding of the temperature dependence of both dc and high-frequency characteristics of InGaP/GaAs heterojunction bipolar transistors (HBT's) is necessary to design stable devices and circuits. This work describes the DC and high-frequency temperature dependence of InGaP/GaAs HBT's. The substrate temperature (T) was varied from 25 to 150 degrees C. The static and dynamic performances of the HBT are degraded at high temperature, due to the reduced of carrier mobility with increasing temperature. The current gain (it) decreases at high temperatures; from 140 at 25 degrees C to 127 at 150 degrees C, while the decreases in the peak Ft is from 110 GHz at 25 degrees C to 68 GHz at 150 degrees C. And a decrease in peak F, is observed from about 165 GHz at 25 degrees C to 53 GHz at 150 degrees C.