Structural and magnetic properties of GaMnAs layers with high Mn-content grown by migration-enhanced epitaxy on GaAs(100) substrates

Ferromagnetic GaMnAs containing up to 10% Mn has been grown by migration-enhanced epitaxy at a substrate temperature of 150 degreesC. The lattice constant of hypothetical zinc-blende structure MnAs is determined to be 5.90 Angstrom, which deviates somewhat from previously reported values. This deviation is ascribed to growth-condition-dependent density of point defects. Magnetization measurements showed an onset of ferromagnetic ordering around 75 K for the GaMnAs layer with 10% Mn. This means that the trend of falling Curie temperatures with increasing Mn concentrations above 5.3% is broken. (C) 2001 American Institute of Physics.