FACET GROWTH IN SELECTIVE AREA EPITAXY OF INP BY MOMBE

InP facet growth near SiO2 mask edges during metalorganic molecular beam epitaxy is studied for various V/III ratios on (100) substrates with 2-degrees misorientation towards (110). While ideal vertical layer growth occurs at high V/III ratio even up to 2 mum growth thickness, oblique (111) planes are kinetically favoured near mask edges at lower V/III ratio. The V/III ratio is a key parameter since it determines the facets with the lowest kinetically limited growth rate at the border of the growing layer. Also the diffusion length of mobile adsorbed species, by which additional features near mask edges and corners are explained, decreases with V/III ratio. Besides interfacet diffusion driven by concentration gradients between facets of different growth rate, there is evidence also for anisotropic diffusion along [011BAR] on (100) InP. We speculate that this is the origin of the fine surface ripples on InP surfaces observed on one side near the SiO2 masks.