Self-assembled InAs quantum dot (QD) based heterostructures have been emerged as a potential candidate for optoelectronic device application over last decade due to the three dimensional carrier confinement. Here, we qualitatively demonstrate the effect of growth rate of both QD and capping layer on the photoluminescence (PL) result of MBE grown InAs/GaAs QD heterostructures. The investigated samples are having 2.7 monolayer (ML) near-surface InAs QDs. The InAs QDs in samples A and B are grown with growth rates of 0.2 and 0.1 ML/sec respectively, whereas growth rate of the GaAs capping layer is kept constant (0.62 μm/hr) in both samples. In sample C, QD and capping layer are grown at 0.2 ML/sec and 1.13 μm/hr, respectively. Sample B exhibited lower full-width half maximum of ground peak (36 nm) as compared to sample A (40 nm). This indicates better homogeneity in dot size distribution in sample B, which has a lower growth rate of QDs. Moreover, sample C with higher growth rate of capping layer showed red-shift in PL as compared to sample A. It can be inferred that the growth rate of capping layer affects the composition of QDs by suppressing In diffusion from QDs towards the capping layer. However, sample C showed decrement in PL intensity and it could be attributed to the dissolution of dots due to higher growth rate of capping layer. There is trade-off in optimization of growth rate variabilities of both QDs and capping layer.
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