A comprehensive study of the effect of in situ annealing at high growth temperature on the morphological and optical properties of self-assembled InAs/GaAs QDs

Abstract

We investigate the effect of in situ annealing during growth pause on the morphological and optical properties of self-assembled InAs/GaAs quantum dots (QDs). The islands were grown at different growth rates and having different monolayer coverage. The results were explained on the basis of atomic force microscopy (AFM) and photo-luminescence (PL) measurements. The studies show the occurrence of ripening-like phenomenon, observed in strained semiconductor system. Agglomeration of the selfassembled QDs takes place during dot pause leading to an equilibrium size distribution. The PL properties of the QDs are affected by the Indium desorption from the surface of the QDs during dot pause annealing at high growth temperature (520°C) subsiding the effect of the narrowing of the dot size distribution with growth pause. The samples having high monolayer coverage (3.4 ML) and grown at a slower growth rate (0.032 ML s −1 ) manifested two different QD families. Among the islands the smaller are coherent defect-free in nature, whereas the larger dots are plastically relaxed and hence optically inactive. Indium desorption from the island surface during the in situ annealing and N. Halder · R. Rashmi · S. Chakrabarti ( ) Centre

Inorganic-Organic Hybrid Nanomaterials for Therapeutic and Diagnostic Imaging Applications

“…Others studies have also shown that the reagents, amount of starting material, and temperature all affect the quality of QDs such as the morphology and optical properties ( i.e. , quantum efficiency) [ 175 , 176 ].…”