Growth temperature dependence of Mn/GaAs surfaces and interfaces

In situ x-ray photoelectron spectroscopy and scanning tunneling microscopy were combined to examine the formation of the reacted region at the Mn/GaAs(001) interface during deposition. Thin films of Mn were grown on GaAs c(4x4) surfaces by molecular beam epitaxy at substrate temperatures of 40, 95, and 250 deg. C. The attenuations of the Ga and As photoemission peak intensities as a function of Mn deposition indicate the formation of a reacted layer at the interface with an average composition of Mn0.6Ga0.2As0.2, and submonolayer coverages of As were found to segregate to the sample surface independent of the growth temperature. The extent of the Mn-Ga-As interfacial reactions that occur during the growth of Mn on GaAs strongly depends upon the growth temperature. At growth temperatures of 95 deg. C and below, the interfacial reacted layer reaches a thickness that is sufficient to limit any additional diffusion of Mn into the GaAs. During growth at 250 deg. C the rate of diffusion is higher and the interfacial reacted layer continues to increase in thickness as the rate of diffusion remains similar to the growth rate for depositions ranging up to hundreds of angstroms