Structural characterization of InN quantum dots grown by Metalorganic Vapour Phase Epitaxy

Abstract

AbstractThe effect of a low temperature GaN capping layer on the structural properties of InN quantum dots is reported. InN quantum dots grown onto sapphire using GaN buffer, with and without low temperature GaN capping layer, have been investigated by atomic force microscopy and transmission electron microscopy. The analysis revealed hexagonal shape quantum dots in both samples. Moreover, the GaN capping layer gives rise to a reduction in the dots aspect ratio. Moiré fringe patterns, obtained in planar view geometry, were used to analyse the strain relaxation of the InN quantum dots. The moiré pattern measurements demonstrated that the uncapped InN quantum dot is almost fully relaxed. These results are related to the formation of a 60° misfit dislocation network in the InN/GaN interface. However, the capping layer not only generated a change of the aspect ratio, but also a decrease in the heterostructure plastic relaxation. The reason of this effect is discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)