Planar heterojunction bipolar transistor with an implanted base

A novel process to fabricate a planar emitter-up AlGaAs-GaAs heterojunction bipolar transistor HBT, has been developed relying on selective base implantation through the emitter and the heterojunction. The selective base definition means that all three transistor contacts can be made from the top surface, thereby making device integration easier because of the planar surface topology. This simple transistor fabrication process was examined using MOCVD material. Transistors with a DC current gain of 120 have been measured.