III-Nitride Tunneling Hot Electron Transfer Amplifier (THETA)

In this chapter, we investigate vertical transistors based on hot electron transport—tunneling hot electron transfer amplifier (THETA). As compared to lateral transport devices such as HEMTs, electron transport can be defined by heterojunction growth at a scale shorter than 10 nm, and output conductance can be controlled through doping and epitaxial engineering. Furthermore, the power dissipation in a vertical device occurs over a volume rather than in a 2D sheet; the local temperature rise is not as significant as in the lateral case. THETA had been previously demonstrated in GaAs systems, and current gain in excess of 10 had been achieved with wide bandgap AlSbAs emitter at room temperature. GaN THETA has been reported in recent years, but the current gain in these devices has remained relatively low.