Photoluminescence spectra of InAs quantum dots embedded in GaAs heterostructure

Self-assembled InAs/GaAs quantum dot (QD) heterostructures grown by solid state molecular beam epitaxy (MBE) were subjected to growth ripening pause of comparatively short durations (0–50 s) at growth temperature (520 °C). Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM) studies indicate that the QD islands increase in size with the growth pause and correspondingly their density decreases. Photoluminescence (PL) studies were carried out on these QDs. Both ground and excited state PL spectra are reported. We present a formalism based on the quantum confinement model and a distribution of dot sizes to explain our results. A minimal set of parameters is employed whose numerical values are obtained from independent experiments and/or microscopic theories. Calculations based on our formalism satisfactorily account for observed PL spectra. The temperature dependence of the PL is also studied and models to explain it are explored.