Effect of n+-GaAs thickness and doping density on spin injection of GaMnAs/n+-GaAs Esaki tunnel junction

TL;DR

This study examines how the thickness and doping density of n+-GaAs affect spin injection efficiency in GaMnAs/n+-GaAs Esaki tunnel junctions, revealing bias-dependent EL polarization behavior.

Contribution

It provides experimental insights into the impact of n+-GaAs layer properties on spin injection efficiency in tunnel junctions, a novel investigation in this context.

Findings

Higher EL polarization in samples with fully depleted n+-GaAs at zero bias

EL polarization is sensitive to bias conditions in the tunnel junction and LED

Sample variations affect the bias dependence of EL polarization

Abstract

We investigated the influence of n+-GaAs thickness and doping density of GaMnAs/n+-GaAs Esaki tunnel junction on the efficiency of the electrical electron spin injection. We prepared seven samples of GaMnAs/n+-GaAs tunnel junctions with different n+-GaAs thickness and doping density grown on identical p-AlGaAs/p-GaAs/n-AlGaAs light emitting diode (LED) structures. Electroluminescence (EL) polarization of the surface emission was measured under the Faraday configuration with external magnetic field. All samples have the bias dependence of the EL polarization, and higher EL polarization is obtained in samples in which n+-GaAs is completely depleted at zero bias. The EL polarization is found to be sensitive to the bias condition for both the (Ga,Mn)As/n+-GaAs tunnel junction and the LED structure.