Investigation of thermal interdiffusion in InAs/In0.15Ga0.85As/GaAs quantum dot-in-a-well heterostructures

An analysis of the effects of rapid thermal annealing on the photoluminescence spectrum of InAs/In0.15Ga0.85As/GaAs Quantum dot-in-a-well heterostructures is presented. The variation of ground state interband transition energies with annealing has been modeled and the effect of varying dot aspect ratios, well indium concentrations and well thicknesses analysed on both peak transition energy and interdiffusion driven blueshift in the photoluminescence spectrum. Our simulations indicate that at low annealing temperatures indium diffusion from InAs dot to InGaAs well dominates, while at higher temperatures indium diffusion from well to GaAs barrier is predominant. Further, we see an increase in strain relaxation as the coverage of dots with InGaAs is increased, and as the indium concentration and/or thickness of InGaAs well is increased. Our model is useful in engineering dot-in-a-well heterostructures with the dual aim of achieving a desired peak wavelength and minimizing blueshift due to annealing.