High current gain, low offset voltage heterostructure emitter bipolar transistors

Heterostructure Emitter Bipolar Transistors (HEBT's) were fabricated with improved characteristics by employing the emitter edge-thinning technique. Optimum design for the n-GaAs emitter and the ledge thickness were used to remove the potential spike and to prevent ledge conduction simultaneously. Current gains as high as 720, which is the highest current gain ever reported for HEBT's, and offset voltages down to 70 mV were obtained. Very large improvement in current gain, especially at low collector current, was obtained by using the emitter edge-thinning technique. >