Temperature dependence of DC and RF characteristics of AlInAs/GaInAs HBT´s

Device characteristics of compositionally graded AlInAs/GaInAs heterojunction bipolar transistors (HBTs) measured and analyzed from cryogenic temperatures up to 250°C are discussed. Excellent stability in DC and RF performance is observed at elevated temperatures, which is desirable for high-speed and high-density integrated circuit applications. DC current gain exhibits about 10% variation over the entire measured temperature range. F_T and f _max at 125°C decreased by approximately 10% from their room-temperature values while improving steadily when the device was cooled down to near-liquid-helium temperature, the common-emitter breakdown voltage is 8.0 V at room temperature and reduces to 7.5 V at 125°C. Likewise, the collector-base breakdown voltage and the base-emitter breakdown voltage reduce by about 0.5 V over the same temperature range. The breakdown voltages increase significantly at cryogenic temperatures. The low turn-on voltage and excellent low-temperature characteristics make the AlInAs/GaInAs HBT attractive for cryogenic applications