Investigation of InP/InGaAs pnp /spl delta/-doped heterojunction bipolar transistor

Abstract

An InP/InGaAs /spl delta/-doped pnp heterojunction bipolar transistor (HBT) has been successfully fabricated and demonstrated for the first time. The addition of a /spl delta/-doped sheet between two undoped spacer layers more effectively eliminates the potential spike at the emitter-base junction, lowers the emitter-collector offset voltage, and increases the effective barrier for electrons, simultaneously. A maximum current gain of 50 and a low offset voltage of 70 mV are obtained, respectively. To our knowledge, the offset voltage of the studied device is the best reported for InP/InGaAs pnp HBTs.