Intersubband carrier scattering in n- and p-Si/SiGe quantum wells with diffuse interfaces

TL;DR

This paper investigates how diffuse interfaces and alloy disorder affect intersubband carrier scattering in Si/SiGe quantum wells, revealing significant impacts on scattering rates and subband energies, with implications for device fabrication tolerances.

Contribution

It introduces a method to calculate growth process tolerances considering diffuse interfaces and analyzes their effects on scattering in Si/SiGe quantum wells.

Findings

Alloy disorder scattering increases with Ge interdiffusion in n-type wells.

Smoothing of the potential significantly alters subband energies and scattering rates.

Scattering remains nearly constant in p-type heterostructures despite interface diffusion.

Abstract

Scattering rate calculations in two-dimensional Si/SiGe systems have typically been restricted to rectangular Ge profiles at interfaces between layers. Real interfaces, however, may exhibit diffuse Ge profiles either by design or as a limitation of the growth process. It is shown here that alloy disorder scattering dramatically increases with Ge interdiffusion in (100) and (111) n-type quantum wells, but remains almost constant in (100) p-type heterostructures. It is also shown that smoothing of the confining potential leads to large changes in subband energies and scattering rates, and a method is presented for calculating growth process tolerances.