Microscopic analysis of interface composition dynamics in m-plane AlInN

We present first microscopic evidence on approximately two monolayers of interfacial indium depletion in one-directionally lattice-matched AlInN grown on m-plane GaN as measured by energy dispersive X-ray spectroscopy. Contrary to other reports, we find no significant incorporation of parasitic gallium into the volume material, but only some spreading of gallium across the GaN/AlInN heterointerface. Using a quantitative description of this behaviour, we conclude that the observed effects are not depending on the crystal orientation, nominal stoichiometry and strain state of the AlInN, but rather represent an inherent characteristic of its growth dynamics, related to the differences in metal-nitrogen binding energies of AlN and InN.