Theory of spin-polarized transport in semiconductor heterojunctions: Proposal for spin injection and detection in silicon

TL;DR

This paper develops a theoretical model for spin-polarized transport in silicon heterojunctions, proposing methods for spin injection and detection despite silicon's weak spin-orbit coupling and indirect gap.

Contribution

It introduces two novel approaches for spin injection and detection in silicon and analyzes their effectiveness through a detailed transport model.

Findings

Equilibrium hole spin polarization significantly alters electron spin and charge dynamics.

Charge current symmetry can be used to detect spin injection in silicon.

The proposed methods are compatible with existing experimental techniques.

Abstract

Spin injection and detection in silicon is a difficult problem, in part because the weak spin-orbit coupling and indirect gap preclude using standard optical techniques. We propose two ways to overcome this difficulty, and illustrate their operation by developing a model for spin-polarized transport across a heterojunction. We find that equilibrium spin polarization of holes leads to a strong modification of the spin and charge dynamics of electrons, and we show how the symmetry properties of the charge current can be exploited to detect spin injection in silicon using currently available techniques.