Electron Transport in Engineered Substrates: Strain, Orientation, and Channel/Insulator Material Effects

Abstract

We present theoretical results regarding electronic transport in different types of `unconventional' substrates and structures: (a) In uniaxially and biaxially strained Si for a variety of substrate, transport-direction and strain orientations, showing that compressive strain on (110) surfaces may enhance simultaneously the electron and hole mobility; (b) In short-channel Si, Ge, and InGaAs bulk and double-gate FETs, showing that at the 15 nm length the `density-of-states' bottleneck reduces drastically the performance of small-mass materials. We also discuss the role of Zener leakage in these small devices, process which is particularly severe in Ge devices; (c) In Si and Ge high-k systems, showing that electron mobility in Ge inversion layers is also seriously affected by high-k phonons, but that the loss of performance -- measured in terms of transconductance -- vanishes at short channel length for both Si and Ge devices.