Demonstration of a graphene-base heterojunction transistor with saturated output current

Abstract

A novel transistor with a graphene base embedded between two n-type silicon emitter and collector layers (graphene-base heterojunction transistor) is fabricated and characterized electrically. The base voltage controlled current of the device flows vertically from the emitter via graphene to the collector. Due to the extremely short transit time for electrons passing the ultimately thin graphene base, the device has a large potential for high-frequency RF applications. The transistor exhibits saturated output currents and a clear modulation of the collector current by means of the graphene base voltage. The vertical transfer current from the emitter via the graphene base to the collector is much lower than expected from device simulations. A comparison of the graphene-base transistor and a reference silicon n-p-n bipolar transistor is performed with respect to the main DC transistor characteristics. A common-emitter gain of larger than one has been achieved for the reference device while the graphene-base transistor so far exhibits a much lower gain.