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Published online by Cambridge University Press: 01 February 2011
The influence of growth sequence on optical and structural properties of InAs/GaAs quantum dots (QD) grown by atomic layer epitaxy was investigated systematically. It is found that growth interruption (GI) after In is more effective than non-GI after In in reducing the density of coalescent dots, and reducing the dot width distribution of the QDs. Meanwhile, dot densities are approximately doubled by non-GI after In. GI after As reduces dot height distribution compared with non-GI after As. Generally, GI after In plays a more critical role than GI after As does in formation of the QDs. The sample grown with In/GI/As/GI sequence shows the lowest 300 K-photoluminescence (PL) linewidth (∼30 meV), high PL peak separation between ground and 1st excited level (∼80 meV). From the result, it is known that In/GI/As/GI is the favorable growth sequence among the sample sets. Temperature dependence of PL linewidth shows that the In/GI/As/GI sample is insensitive to cryostat temperature and it is attributed to weak wetting effect. Thinner wetting layers shown in a cross-sectional TEM image supports this.