Effects of interdiffusion on the luminescence of InAs/GaAs quantum dots covered by InGaAs overgrowth layer

We have studied the effects of postgrowth rapid thermal annealing on the op tical properties of 3-nm-height InAs/GaAs quantum dots covered by 3-nm-thic k InxGa1-xAs (x = 0, 0.1, and 0.2) overgrowth layer. At higher annealing te mperature (T greater than or equal to 750 degreesC), the photoluminescence peak of InGaAs layer has been observed at lower-energy side of the InAs qua ntum-dot peak. In addition, the blueshift in photoluminescence (PL) emissio n energy is found to he similar for all samples with increasing the anneali ng temperature from 650 to 850 degreesC. However, the trend of narrowing of photoluminescence linewidth is significantly different for InAs quantum do ts with different In mole fractions in InGaAs overgrowth layer. These resul ts suggest that the intermixing in the lateral direction plays an important role in helping to understand the modification of optical properties induc ed by rapid thermal annealing. (C) 2000 Elsevier Science B.V. All rights re served.