Effect of Mn on the low temperature growth of GaAs and GaMnAs

With the combined use of reflection high energy electron diffraction (RHEED) and scanning tunneling microscope, the growing surfaces of GaAs and GaMnAs were investigated. At the start of GaAs growth at low temperature ∼250°C, RHEED oscillation indicated larger growth rate, which decreased gradually to reach the constant value, identical to that for the high temperature growth. The shift in the growth rate depends on excess As coverage pre-adsorbed on the substrate. Mn addition lowered the degree of the shift and improved the epitaxy.