그래핀을 베이스로 사용한 열전자 트랜지스터의 특성

Abstract

Graphene has a monolayer crystal structure formed with C-atoms and has been used as a base layer of HETs (hot electron transistors). Graphene HETs have exhibited the operation at THz frequencies and higher current on/off ratio than that of Graphene FETs. In this article, we report on the preliminary results of current characteristics from the HETs which are fabricated utilizing highly doped Si collector, graphene base, and 5 nm thin tunnel layers between the base and Ti emitter. We have observed E-B forward currents are inherited to tunneling through layers, but have not noticed the Schottky barrier blocking effect on B-C forward current at the base/collector interface. At the common-emitter configuration, under a constant between 0~1.2V, has increased linearly with for indicating the saturation region. As the increases further, a plateau of vs. has appeared slightly at , denoting forward-active region. With further increase of , has kept increasing probably due to tunneling through thin Schottky barrier between B/C. Thus the current on/off ration has exhibited to be 50. To improve hot electron effects, we propose the usage of low doped Si substrate, insertion of barrier layer between B/C, or substrates with low electron affinity.