High gain lateral heterojunction bipolar transistors and application to optoelectronic integration

Refinements in the geometry of a novel AlGaAs lateral heterojunction bipolar transistor structure that have made it possible to greatly improve the DC characteristics of these devices are described. By reducing the base dimensions to 0.35 mu m and improving the abruptness of the grading at the base-emitter p-n junction, maximum current gains in excess of 600 have been achieved. Demonstration of these values of gain establishes the viability of this device architecture for making a wide variety of electronically functional circuits. The improvements have been realized with only a relatively small penalty in increased difficulty of device fabrication. In addition, the complete planarity of the fabrication process for these devices makes them very attractive for optoelectronic integration applications.<>