Focusing of Spin Polarization in Semiconductors by Inhomogeneous Doping

TL;DR

This paper investigates how inhomogeneous doping in semiconductors can focus and amplify electron spin polarization using electric fields, with potential applications in spintronic device design.

Contribution

It introduces a numerical analysis of spin polarization propagation across doping boundaries, demonstrating polarization compression and amplification without interface losses.

Findings

Spin polarization can be compressed and amplified near doping boundaries.

No significant spin loss occurs at doping boundaries without material interfaces.

The mechanism is promising for designing advanced spintronic devices.

Abstract

We study the evolution and distribution of non-equilibrium electron spin polarization in n-type semiconductors within the two-component drift-diffusion model in an applied electric field. Propagation of spin-polarized electrons through a boundary between two semiconductor regions with different doping levels is considered. We assume that inhomogeneous spin polarization is created locally and driven through the boundary by the electric field. The electric field distribution and spin polarization distribution are calculated numerically. We show that an initially created narrow region of spin polarization can be further compressed and amplified near the boundary. Since the boundary involves variation of doping but no real interface between two semiconductor materials, no significant spin-polarization loss is expected. The proposed mechanism will be therefore useful in designing new spintronic devices.