InAs quantum dots grown on GaAs (100) surfaces subjected to novel in-situ treatments

Abstract

Novel in-situ treatments were performed to GaAs(100) surfaces in order to improve the size homogeneity of self-assembled InAs quantum dots (QDs). The treatments consisted in exposing the GaAs surfaces at high temperature for 10 seconds with the As$_{4}$- shutter closed. In the first experiment, the GaAs surface was just kept under no fluxes during 10 seconds, while in another growth the Si shutter was opened during the As$_{4}$ flux interruption. Both experiments were compared with a conventionally grown sample. Remarkable differences in the growth kinetics were observed when the InAs deposition was performed on different treated GaAs surfaces. The thermal treatment performed under no Si-flux extended the two to three-dimensional growth transition at much larger InAs thickness. On the contrary, the Si-treated sample showed an earlier lattice relaxation as compared with the reference sample. As for the final topology of the samples both treatments decreased the QDs diameter and height dispersion as compared with the conventionally grown sample. Therefore, a significant improvement on the size distribution of QDs was induced by the novel in-situ treatments, which also reduced the full width at half maximum (FWHM) of the photoluminescence (PL) emission spectra. Additionally, PL experiments showed a clear correlation between the dots size increase and the emission peak redshift observed for the QDs grown on GaAs surfaces subjected to the different treatments.