Reduction of Spin Injection Efficiency by Interface Defect Spin Scattering in ZnMnSe/AlGaAs−GaAs Spin-Polarized Light-Emitting Diodes

Abstract

We report the first experimental demonstration that interface microstructure limits diffusive electrical spin-injection efficiency across heteroepitaxial interfaces. An inverse correlation between spin-polarized electron injection efficiency and interface defect density is demonstrated for $\mathrm{Z}\mathrm{n}\mathrm{M}\mathrm{n}\mathrm{S}\mathrm{e}/\mathrm{A}\mathrm{l}\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}\mathrm{\text{−}}\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}$ spin-polarized light-emitting diodes that exhibit quantum well spin polarizations up to 85%. A theoretical treatment shows that the suppression of spin injection due to interface defects results from the contribution of the defect potential to the spin-orbit interaction, which increases the spin-flip scattering.