Gate-length dependence of negative differential resistance in ridge-type InGaAs/InAlAs quantum wire field-effect transistor

Abstract

We investigate the gate-length dependence of negative differential resistance (NDR) in a ridge-type InGaAs/InAlAs quantum wire field-effect transistor with a gate varying from 50 nm to 1 μm in length. The gate leakage current is detectable only with the onset of NDR and increases with larger gate bias. The NDR could be attributed to the real space transfer of channel carrier into the barrier layer by gate field-assisted tunneling. The NDR characteristics are dependent strongly on gate length. The improvement in NDR characteristic in terms of peak-to-valley current ratio and onset voltage (VNDR) is observed clearly with the reduction of gate length. The QWIR-FETs with shorter gate length show the NDR even at room temperature. The improvement in NDR characteristic is attributed to a velocity overshoot enhanced by the suppression of scattering probability.