Droplet Epitaxy of InAs Nanocrystals on GaN/GaAs : Structure and Mechanical and Thermal Properties of Condensed Matter

概要

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The growth of InAs nanocrystals fabricated on GaAs by means of droplet epitaxy in a metal-organic chemical vapour-deposition chamber was investigated. To prevent deterioration of the droplet/substrate interface a nitride passivation layer was introduced. For this purpose both, nitridation of GaAs and GaN growth at different temperatures have been applied, In all nitrided samples and when GaN was grown at T_g = 450℃, deep pit-like defects have been found in the GaAs below the InAs islands, caused by In that diffused from the droplets into the substrate along the {111} planes. Only the growth of a thin cubic GaN layer at T_g = 550℃ effectively prevented this indiffusion of indium into the substrate. The InAs islands contained stacking faults and twins that arose from defects in the underlying GaN layer. Their sidewalls do not only consist of (001) and {111} facets, but also of the commonly not observed {110} and even {111} facets. The frequent occurrence of holes at the center base of the InAs islands is discussed within a growth model for the transformation of In droplets to InAs nanocrystals.
社団法人応用物理学会の論文
2001-11-15