Altering the Optical Properties of GaAsSb-Capped InAs Quantum Dots by Means of InAlAs Interlayers

摘要

In this work, we investigate the optical properties of InAs quantum dots (QDs) capped with composite In~(0.15)Al~(0.85)As/GaAs~(0.85)Sb~(0.15)strain-reducing layers (SRLs) by means of high-resolution X-ray diffraction (HRXRD) and photoluminescence (PL) spectroscopy at 77?K. Thin In~(0.15)Al~(0.85)As layers with thickness t ?=?20??, 40??, and 60?? were inserted between the QDs and a 60-?-thick GaAs~(0.85)Sb~(0.15)layer. The type II emissions observed for GaAs~(0.85)Sb~(0.15)-capped InAs QDs were suppressed by the insertion of the In~(0.15)Al~(0.85)As interlayer. Moreover, the emission wavelength was blueshifted for t ?=?20?? and redshifted for t ?≥?40?? resulting from the increased confinement potential and increased strain, respectively. The ground state and excited state energy separation is increased reaching 106?meV for t ?=?60?? compared to 64?meV for the QDs capped with only GaAsSb SRL. In addition, the use of the In~(0.15)Al~(0.85)As layers narrows significantly the QD spectral linewidth from 52 to 35?meV for the samples with 40- and 60-?-thick In~(0.15)Al~(0.85)As interlayers.