Optimizing the growth of 1.3 μm InAs/GaAs quantum dots

Scanning probe microscopy has been used to show that InAs/GaAs quantum dots (QD’s) can be grown (at very low growth rates) using continuous InAs depositions of up to five monolayers (ML) without QD coalescence. These growth conditions result in relatively large coherent QD’s which exhibit strong room temperature photoluminescence (PL) at a wavelength of 1.3 μm when capped with GaAs. The average QD volume prior to capping increases monotonically with InAs coverage up to 5 ML, but the PL emission wavelength saturates around 1.3 μm after ∼3 ML. This is due to the presence of much larger, irregular and plastically relaxed three-dimensional islands which act as sinks for additional deposited material and do not participate in optical emission.