Self-organized type-II In0.55Al0.45As/Al0.50Ga0.50As quantum dots realized on GaAs(311)A

Self-organized ${\mathrm{In}}_{\mathrm{0.55}}{\mathrm{Al}}_{\mathrm{0.45}}{\mathrm{As/Al}}_{\mathrm{0.50}}{\mathrm{Ga}}_{\mathrm{0.50}}\mathrm{As}$ quantum dots are grown by the Stranski–Krastanow growth mode using molecular beam epitaxy on the $\mathrm{GaAs}\text{(311)A}$ substrate. The optical properties of type-II InAlAs/AlGaAs quantum dots have been demonstrated by the excitation power and temperature dependence of photoluminescence spectra. A simple model accounting for the size-dependent band gap of quantum dots is given to qualitatively understand the formation of type-II ${\mathrm{In}}_{\mathrm{0.55}}{\mathrm{Al}}_{\mathrm{0.45}}{\mathrm{As/Al}}_{\mathrm{0.50}}{\mathrm{Ga}}_{\mathrm{0.50}}\mathrm{As}$ quantum dots driven by the quantum-confinement-induced $\mathrm{\Gamma \to X}$ transition. The results provide new insights into the band structure of InAlAs/AlGaAs quantum dots.