Electron transport in Si/SiGe modulation-doped heterostructures using Monte Carlo simulation

TL;DR

This study uses Monte Carlo simulation to analyze electron transport and mobility in Si/SiGe heterostructures, matching experimental data and exploring effects of structure parameters and gating.

Contribution

It provides detailed simulation-based insights into electron mobility in Si/SiGe heterostructures, including effects of spacer thickness and gating, with validation against experimental results.

Findings

Mobility ranges from 1100 to 2800 cm²/Vs depending on doping and density.

Mobility is influenced by spacer layer thickness and gate voltage.

Gated structures show higher mobility than ungated ones.

Abstract

The electron transport in the two-dimensional gas formed in tensile-strained Si1-xGex/Si/Si1-xGex heterostructures is investigated using Monte Carlo simulation. At first the electron mobility is studied in ungated modulation doped structures. The calculation matches very well the experimental results over a wide range of electron density. The mobility typically varies between 1100 cm2/Vs in highly-doped structures and 2800 cm2/Vs at low electron density. The mobility is shown to be significantly influenced by the thickness of the spacer layer separating the strained Si channel from the pulse-doped supply layers. Then the electron transport is investigated in a gated modulation-doped structure in which the contribution of parasitic paths is negligible. The mobility is shown to be higher than in comparable ungated structures and dependent on the gate voltage, as a result of the electron density dependence of remote impurity screening.