Reducing the current crowding effect in bipolar transistors by tunnel diode emitter design

摘要

We present an emitter design capable of reducing the current crowding effect in high power heterojunction bipolar transistors. An Esaki diode, vertically integrated to the transistor, limits the maximal emitter current density. The current crowding reduction is observed using effective base resistance measurements. Advantages in protecting high power transistors against thermal instabilities are discussed and the increased safe operation range is demonstrated.