Impact of the cap layer on the electronic structures and optical properties of self-assembled InAs/GaAs quantum dots

Cap layer impact on the electronic structures and optical properties of self-assembled InAs/GaAs quantum dots is theoretically studied within the framework of Burt and Foreman's eight-band effective-mass Hamiltonian. A numerically stable finite difference scheme for this nonsymmetrized Hamiltonian and an efficient implementation of Jacobi-Davidson eigensolver for the resulting matrix are proposed. Our theoretical results show that as the cap layer thickness increases, the photoluminescence (PL) peak position exhibits a monotonous blueshift and the PL intensity enhances. These results are accounted for by the strain modified band edges and the space separation of electron and heavy-hole wave functions in the growth direction. Dot shape and size effects are also discussed. Our calculations are in good agreement with recent experimental findings.