Low-temperature annealing effects on (Ga,Mn)As/Zn-GaAs superlattice structures grown on GaAs(0 0 1) substrates

Abstract

(Ga,Mn)As/Zn-doped GaAs superlattices (SLs) have been prepared by molecular beam epitaxy (MBE), and the effect of low-temperature thermal annealing on their structural, electrical, and magnetic properties has been investigated. The SL structures studied in this work consists of 5-periods of 20-nm (Ga,Mn)As/5-nm GaAs. In order to introduce extra holes in (Ga,Mn)As layers, the GaAs spacer layers were doped with Zn acceptor atoms. Low-temperature thermal annealing was also performed to increase the hole concentration by reducing lattice defects like Mn interstitials and As antisite defects in (Ga,Mn)As layers. As-grown SL sample showed a ferromagnetic transition temperature T C of ∼50 K, and the presence of noticeable abrupt change in magnetization around ∼35 K in the M– T curve which is possibly due to the rotation of in-plane uniaxial anisotropy with changing temperature. Low-temperature annealing led to an increase in T C up to 65 K accompanied with a decrease in the resistivity.