Effect of stress on structural transformations in GaMnAs.

Granular GaAs:(Mn, Ga)As films were prepared by annealing at 500 degrees C under ambient and enhanced hydrostatic pressure (1.1 GPa), of Ga(1-x)Mn(x)As/GaAs layers (x = 0.025, 0.03, 0.04, 0.05 and 0.063) grown by molecular beam epitaxy method at 230 degrees C. Layers were fully strained in respect to the substrate before and after treatment. Strain change, from compressive to tensile, related to creation of MnAs inclusions of zinc blende structure, was detected after sample annealing. Mn concentration remained unchanged after annealing under ambient and enhanced hydrostatic pressure. Distinct influence of hydrostatic pressure applied during annealing on strain as well as on interface roughness has been found.