A p-n-p AlGaAs heterojunction bipolar transistor for high-temperature operation

Successful operation of a p-n-p AlGaAs heterojunction bipolar transistor at temperatures up to 800 K (527 °C) has been achieved. The device was fabricated from molecular-beam epitaxy grown material and features an Al0.45Ga0.55As emitter and Al0.25Ga0.75As base and collector regions. At room temperature a common emitter current gain of 12 is obtained, which reduces to ∼3 at 800 K. Weak emission of light is seen from the base region with λ=7170 Å at 300 K, in agreement with the expected band gap for Al0.25Ga0.75As of 1.74 eV.