Photoluminescence characteristics of self-assembled InAs quantum dots capped with different strain reducing layer

Self-assembled InAs quantum dots (QDs) overgrown by different strain reducing layer have been prepared on GaAs substrate by molecular beam epitaxy (MBE). Photoluminescence (PL) measurements shows that PL intensity is enhanced by In xGa 1-xAs cap layer, which may be attributed by reducing strain and defect among the QDs. However, the larger x (x ≥ 0.3) may result in a lower material quality of excessive relaxation and generating an interface potential barrier near QDs. It has been found that the carriers may migrate between GaAs barrier and InAs QDs, while the interface potential barrier retards the migration. It has been found that the PL decay spectra of InAs QDs with a low-In-component InGaAs or AlAs cay layer follow the second exponential decay process. Time-resolved PL measurements were also used to analyze the special PL decay of InAs QDs with different strain reducing layer.