Metal–Organic Vapor Phase Epitaxial Growth Condition Dependences of MnAs Nanocluster Formation on GaInAs (111)A Surfaces

The authors report that the formation of MnAs nanoclusters (NCs) on GaInAs (1 1 1)A surfaces strongly depends on metal-organic vapor phase epitaxial growth conditions. It was confirmed from the atomic force microscope observation that deep holes were formed on the surfaces under low V/Mn ratio and high growth temperature conditions, in addition to the formation of MnAs NCs. From the results of cross-sectional transmission electron microscope observation, these deep holes were formed on the underlying GaInAs layers, and MnAs NCs were embedded in the GaInAs (1 1 1)A layers. The formation of these embedded MnAs NCs was possibly caused by the phenomenon of "endotaxy". From the experimental results of thermal treatments of the samples, it was revealed that the deep holes were formed on the GaInAs (1 1 1)A surfaces even after the thermal annealing in the atmosphere of Mn source gas and hydrogen. Therefore, we concluded that high AsH(3) partial pressure (V/Mn ratio) conditions were required for the MnAs growth on GaInAs (1 1 1)A surfaces.