The InGaAs surface quantum dots grown on GaAs surface without a capping layer (surface quantum dots, SQDs) are expected to play an important role for sensor applications due to their special surface sensitive properties. In this research, we investigated the photoluminescence (PL) characteristics of such In0.35Ga0.65As/GaAs SQDs with a layer of buried InGaAs QDs (BQDs) as reference. The uncapped InGaAs SQDs are integrated into a hybrid nanostructure with SQDs and buried quantum dots (BQDs) spaced by a 70 nm GaAs layer. Due to this thick GaAs spacer, we assert there is no quantum coupling between the SQDs and BQDs so that each layer of QDs has independent emission. The PL spectra show that the SQD PL intensity is far less than BQDs at low temperature but exceeds BQDs at high temperature, indicating a possible carrier transfer between the SQDs and surface states. With increasing excitation intensity, the PL spectra show clearly broaden on the high energy side and a blueshift for both the SQDs and BQDs. Therefore, there is lateral carrier transfer among each layer of QDs due to their high areal density. The intra-layer carrier transfer among SQDs as well as the inter-layer carrier transfer between SQDs and surface states attribute to carriers dynamics that make the SQDs having optical performance very different from the BQDs.
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