Analysis of the Transport Process Providing Spin Injection through an Fe/AlGaAs Schottky Barrier

TL;DR

This study demonstrates that tunneling through a Fe/AlGaAs Schottky barrier enables efficient electrical spin injection into GaAs quantum wells, with experimental evidence supporting theoretical predictions.

Contribution

It provides experimental confirmation that tunneling is the primary mechanism for spin injection from metal to semiconductor in Fe/AlGaAs structures.

Findings

Achieved 32% electron spin polarization in GaAs quantum well.

Confirmed single step tunneling as the dominant transport mechanism.

Identified phonon signatures supporting tunneling process.

Abstract

Electron spin polarizations of 32% are obtained in a GaAs quantum well via electrical injection through a reverse-biased Fe/AlGaAs Schottky contact. An analysis of the transport data using the Rowell criteria demonstrates that single step tunneling is the dominant transport mechanism. The current-voltage data show a clear zero-bias anomaly and phonon signatures corresponding to the GaAs-like and AlAs-like longitudinal-optical phonon modes of the AlGaAs barrier, providing further evidence for tunneling. These results provide experimental confirmation of several theoretical analyses indicating that tunneling enables significant spin injection from a metal into a semiconductor.