Submicron AlGaAs/GaAs heterojunction bipolar transistor process with high current gain

A new self-aligned process is developed to obtain sub-micron high performance AlGaAs/GaAs HBTs which can maintain a high current gain for emitter sizes on the order of 1 μm². A DC current gain larger than 30 can be typically obtained for HBTs with 0.5x2 μm² emitter-base junction area at sub-mA collector currents. The high current gain at low collector current level and a small device area comparable to silicon bipolar transistors make these devices suitable for LSI applications.