Abstract
Stacking growth of the InGaAs quantum dots (QDs) on top of a carrier injection layer is a very useful strategy to develop QD devices. This research aims to study the carrier injection effect in hybrid structures with a layer of In0.4Ga0.6As surface quantum dots (SQDs), coupled to an injection layer of either one layer of In0.4Ga0.6As buried QDs (BQDs) or an In0.15Ga0.85As quantum well (QW), both through a 10 nm GaAs thin spacer. Spectroscopic measurements show that carrier capture and emission efficiency for SQDs in the BQD injection structure is better than that of the QW injection, due to strong physical and electrical coupling between the two QD layers. In the case of QW injection, although most carriers can be collected into the QW, they then tunnel into the wetting layer of the SQDs and are subsequently lost to surface states via non-radiative recombination. Therefore, the QW as an injection source for SQDs may not work as well as the BQDs for stacking coupled SQDs structures.
Highlights
Received: 22 January 2022Self-assembled semiconductor quantum dots (QDs) in the In(Ga)As/GaAs family have great potential to enable high-performance opto-electronic devices for a wide variety of applications [1,2,3,4]
For InGaAs surface QDs (SQDs) directly exposed to the environment, there are a large number of dangling bonds on the surface [5,6]
Sample B is the same as sample A, except that the buried QDs (BQDs) layer was replaced with a 12.5 nm In0.15 Ga0.85 As quantum well (QW), deposited at 510 ◦ C to form the injection layer
Summary
Received: 22 January 2022Self-assembled semiconductor quantum dots (QDs) in the In(Ga)As/GaAs family have great potential to enable high-performance opto-electronic devices for a wide variety of applications [1,2,3,4]. For InGaAs surface QDs (SQDs) directly exposed to the environment, there are a large number of dangling bonds on the surface [5,6]. The. InGaAs SQDs undergo oxidation quite fast so that they are covered by a very thin oxidation layer. InGaAs SQDs undergo oxidation quite fast so that they are covered by a very thin oxidation layer Both the surface dangling bonds and the oxide layer give rise to highdensity localized surface states and trapped carriers. As a result of these trapped carriers, SQDs respond very sensitively, either optically or electrically to changes in the surface environment [7,8,9]. A recent surge in research into the surface-sensitive performance of InGaAs SQDs has been reported [12,13,14,15]
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