Metallic behavior in Si/SiGe 2D electron systems

TL;DR

This paper develops a theoretical model explaining the metallic behavior in low-density Si/SiGe 2D electron systems, showing that 2D screening of impurity disorder causes the observed temperature-dependent resistivity, matching experimental data.

Contribution

It provides a comprehensive theoretical explanation for 2D metallic behavior in Si/SiGe systems based on screening effects, aligning with experimental observations.

Findings

The theory matches experimental resistivity data across various conditions.

Screening of impurity disorder explains the metallic temperature dependence.

Model accurately predicts behavior in fully spin-polarized systems.

Abstract

We calculate the temperature, density, and parallel magnetic field dependence of low temperature electronic resistivity in 2D high-mobility Si/SiGe quantum structures, assuming the conductivity limiting mechanism to be carrier scattering by screened random charged Coulombic impurity centers. We obtain comprehensive agreement with existing experimental transport data, compellingly establishing that the observed 2D metallic behavior in low-density Si/SiGe systems arises from the peculiar nature of 2D screening of long-range impurity disorder. In particular, our theory correctly predicts the experimentally observed metallic temperature dependence of 2D resistivity in the fully spin-polarized system.