Monte Carlo simulation of InAs HEMTs considering strain and quantum confinement effects

Abstract

We carried out Monte Carlo simulation of In0.53Ga0.47As/strained-InAs/In0.53Ga0.47As composite channel high electron mobility transistors (HEMTs) considering strain and quantum confinement effects in very thin InAs layer. We calculated the unstrained and the strained band structures of InAs. We also considered the self-consistent analysis of 2-dimensional electron gas (2DEG) by solving Schrödinger and Poisson equations. With considering the effect of 2DEG, the drain-source current Ids decreases. However, the negative threshold voltage shift due to the short-channel effects is not affected by considering 2DEG. The threshold voltage shift occurs in the region Lg/d < ~5 (Lg: gate length, d: sum of the barrier and channel layer thicknesses). We also obtained the cutoff frequency fT values. At a gate length Lg of 20 nm, the calculated fT values were 943 GHz without 2DEG and 813 GHz with 2DEG. The trend of the fT values with Lg reflects that of the electron velocities mainly. The present simulation results indicate that the record fT might be obtained by reducing Lg to around 20 nm for In0.53Ga0.47As/strained-InAs/In0.53Ga0.47As channel HEMTs.