Increase in current density at 25-nm-wide emitter for InP hot-electron transistors without base layer

A narrow emitter is effective in reducing power consumption in electron devices. Moreover, it can provide high-speed operation. As one of such devices, we proposed a hot-electron transistor without a base layer [1]. In this device, hot electrons generated by a heterostructure launcher pass through only an intrinsic semiconductor, resulting in the propagation of electrons without scattering. Because a forward-biased gate on the intrinsic propagation region modulates the potential of the launcher, a narrow emitter is required to create a uniform potential. As described in our former report [2], we fabricated a 25-nm-wide emitter and the transistor action was observed. However, the observed current density for current amplification was around 10 A/cm2, although resonant tunneling diode (RTD) using the same epitaxial structure shows a 1 kA/cm2 peak current density. To exhibit high-speed performance without scattering, high current density in a narrow emitter is essential.