We present first-principles calculations for $m$-plane and $c$-plane ${\text{In}}_{0.25}{\text{Ga}}_{0.75}\text{N}$ surfaces. The results elucidate the dependence of indium incorporation on growth conditions. For both surfaces the calculations indicate that In incorporation is energetically favorable provided the surface is wetted by In adlayers rather than passivated by hydrogen and ${\text{NH}}_2$ groups. Growth of an ${\text{In}}_{0.25}{\text{Ga}}_{0.75}\text{N}$ alloy therefore requires that the chemical potential of hydrogen be kept low. The results predict that a reduction in the abundance of hydrogen can lead to greater In incorporation on the $m$ plane as well as the $c$ plane.

• Received 31 October 2008

DOI:https://doi.org/10.1103/PhysRevB.79.041306