Indium adsorption and incorporation mechanisms in AlN

Abstract

Density functional theory calculations are implemented in order to scrutinize indium adsorption and incorporation mechanisms in polar AlN. Indium adsorption is promoted on both polarity surfaces and adatom kinetics calculations indicate lower diffusion barriers of indium along the prismatic 〈$11\bar{2}0$〉 directions on (0001) as well as ($000\bar{1}$) AlN. The latter is correlated to experimental observations of In_0.24Al_0.76N grown by metal organic vapour phase epitaxy, demonstrating indium concentration along the facet junctions of V-defects. This can be attributed to In surface diffusion along the 〈$11\bar{2}0$〉 directions of the pyramidal facets. Surface thermodynamics reveal a manifold behaviour of indium in polar AlN surfaces, significantly affected by polarity, growth stoichiometry as well as surface termination. In particular, N-rich growth conditions enhance indium incorporation on Al-terminated surfaces of both polarities, leading up to full monolayer coverage. Incorporation on N-terminated (0001) and ($000\bar{1}$) surfaces is hindered independent of growth stoichiometry.