Magnetic Properties and Surface Morphology of MnAs Thin Films Grown by MBE on GaAs(111) Substrates

We formed a ~23-nm-thick MnAs thin film on an epi-ready semi-insulating GaAs(1 11) substrate by molecular beam epitaxy at a growth temperature Ts of 250?C. Streaky in-situ reflection high-energy electron diffraction patterns were obtained during the entire growth process indicating layer-by-layer growth. High-resolution X-ray diffraction revealed two growth orientations, (0001) and (10-11). Magneto metry measurements performed using a superconducting quantum interference device magnetometer revealed a Curie temperature Tc of ~355?C and a large difference in the in-plane and out-of-plane M-H characteristics, even at room temperature. Atomic force microscopy images contained hexagonal patterns or portions, suggesting that the main growth direction is (0001).