InP/InGaAs heterojunction bipolar transistors with superlattice emitter structure

A heterojunction bipolar transistor with superlattice emitter structure based on InP/InGaAs material system has been demonstrated. Two devices with different period of superlattice and emitter thickness were proposed. By introducing the superlattice into the emitter, the confinement of holes is enhanced. Experimentally, for higher periods of superlattice, the current gain is enhanced and more stable temperature-dependent characteristics are observed. The common-emitter current gains up to 170 and 54 are obtained for the studied devices with emitter thickness of 800/spl Aring/ and 150/spl Aring/, respectively.