Growth by molecular beam epitaxy of self-assembled InAs quantum dots on InAlAs and InGaAs lattice-matched to InP

Abstract

The authors report the results of a detailed study of the effect of growth conditions, for molecular beam epitaxy, on the structural and optical properties of self-assembled InAs quantum dots (QDs) on In0.524Al0.476As. InAs QDs both buried in, and on top of, In0.524Al0.476As were analyzed using photoluminescence (PL) and atomic force microscopy. InAs QD morphology and peak PL emission wavelength both scale linearly with deposition thickness in monolayers (MLs). InAs deposition thickness can be used to tune QD PL wavelength by 170nm/ML, over a range of almost 700nm. Increasing growth temperature from 440to480°C results in a linear decrease in QD size and a blueshift in peak emission wavelength of 3.5nm∕°C. This is a direct result of the temperature dependence of the In-sticking coefficient. InAs deposited on InP-lattice-matched In0.532Ga0.468As forms larger, lower-density features with longer PL wavelength, as expected from a consideration of the effects of In segregation and intermixing on strain and surface roughness. Choice of buffer material is shown to be critical to QD characteristics.