(Ga,Mn)As grown on (311) GaAs substrates: Modified Mn incorporation and magnetic anisotropies

We report the results of a detailed study of the structural, magnetic, and magnetotransport properties of as-grown and annealed Ga0.91Mn0.09As thin films grown on (311)A and (311)B GaAs substrates. The high Curie temperature and hole density of the (311)B material are comparable to those of GaMnAs grown on (001) GaAs under the same growth conditions, while they are much lower for the (311)A material. We find evidence that Mn incorporation is more efficient for (311)B than for (001) and significantly less efficient for (311)A which is consistent with the bonding on these surfaces. This indicates that growth on (311B) may be a route to increased Curie temperatures in GaMnAs. A biaxial magnetic anisotropy is observed for the (311) material with easy axes along the [010] and [001] out-of-plane directions. An additional uniaxial in-plane anisotropy is also observed with the easy axis along [01 (1) over bar] for the (311)A material, and along [(2) over bar 33] for the (311)B material. This observation may be of importance for the resolution of the outstanding problem of the origin of uniaxial anisotropy in (001) GaMnAs.