Impact of low-temperature cover layer growth of InAs/GaAs quantum dots on their optical properties

The effect of low-temperature InGaAs/GaAs cover layer growth of InAs quantum dots on their optical and structural properties was investigated. Photoluminescence intensity depended heavily on the growth temperature and thickness of the low-temperature cover layer and decreased as the number of dislocations formed directly above InAs quantum dots increased. These dislocations are formed at the initial stage of high-temperature GaAs growth, originating from pits that remain on the surface after the growth of the low-temperature cover layer and subsequent annealing. To ensure a high-quality InAs quantum dot structure free from dislocations, it is important to obtain a highly flat surface with suppressed pits after low-temperature cover layer growth and subsequent annealing.