Experimental determination of local Strain effect on InAs/GaAs self-organized quantum dots

Abstract

The energy barrier at InAs/GaAs interface due to the built-in strain in self-organized system has been determined experimentally. Such a barrier has been predicted by previous theories. From the deep-level transient spectroscopy (DLTS) measurements, we have obtained the electron and hole energy levels of quantum dots ${E}_{e}^{\mathrm{Q}\stackrel{\ensuremath{\rightarrow}}{D}\mathrm{GaAs}}=0.13\mathrm{eV}$ and ${E}_{h}^{\mathrm{Q}\stackrel{\ensuremath{\rightarrow}}{D}\mathrm{GaAs}}=0.09\mathrm{eV}$ relative to the bulk unstrained GaAs band edges ${E}_{c}$ and ${E}_{v}.$ DLTS measurements have also provided evidence to the existence of the capture barriers of quantum dots for electron ${E}_{\mathrm{eB}}=0.30\mathrm{eV}$ and hole ${E}_{\mathrm{hB}}=0.26\mathrm{eV}.$ The barriers can be explained by the apexes appearing in the interface between InAs and GaAs caused by strain. Combining the photoluminescence results, the band structures of InAs and GaAs have been determined.