Electron Scattering in Buried InGaAs MOSFET Channel with HfO₂ Gate Oxide

Abstract

Group III-V semiconductor materials are being studied as potential replacements for conventional CMOS technology due to their better electron transport properties. However, the excess scattering of carriers in MOSFET channel due to high-k gate oxide interface significantly depreciates the benefits of III-V high-mobility channel materials. We present results on Hall electron mobility of buried QW structures influenced by remote scattering due to InGaAs/HfO₂ interface. Mobility in In_0.77Ga_0.23As QWs degraded from 12000 to 1200 cm²/V-s and the mobility vs. temperature slope changed from T^-1.2 to almost T^+1.0 in 77-300 K range when the barrier thickness is reduced from 50 to 0 nm. This mobility change is attributed to remote Coulomb scattering due to charges and dipoles at semiconductor/oxide interface. Elimination of the InGaAs/HfO₂ interface via introduction of SiO_x interface layer formed by oxidation of thin a-Si passivation layer was found to improve the channel mobility. The mobility vs. sheet carrier density shows the maximum close to 2×10¹² cm^-2.