Rapid diffusion of electrons in GaMnAs

TL;DR

This study uses ultrafast transient-grating measurements to investigate electron diffusion in GaMnAs, revealing rapid electron diffusion with implications for its electronic properties and mobility.

Contribution

First direct measurement of ultrafast electron diffusion in GaMnAs, showing rapid diffusion rates and providing insights into its electronic structure.

Findings

Electron lifetime of 8 ps at 80 K and 5 ps at 15 K.

Electron diffusion coefficients of about 70 and 60 cm²/s.

Electronic mobility likely exceeds 7,700 cm²/Vs.

Abstract

We report ultrafast transient-grating measurements, above and below the Curie temperature, of the dilute ferromagnetic semiconductor (Ga,Mn)As containing 6% Mn. At 80 K (15 K), we observe that photoexcited electrons in the conduction band have a lifetime of 8 ps (5 ps) and diffuse at about 70 cm2/s (60 cm2/s). Such rapid diffusion requires either an electronic mobility exceeding 7,700 cm2/Vs or a conduction-band effective mass less than half the GaAs value. Our data suggest that neither the scattering rate nor the effective mass of the (Ga,Mn)As conduction band differs significantly from that of GaAs.