Investigation of intrinsic defects and their distribution in CdSe/ZnSe quantum dot structures

The intrinsic defects and their distribution in CdSe/ZnSe self-assembled quantum dot heterostructures grown under variation of VI/II group beam pressure ratio are investigated by luminescent and high-resolution X-ray diffraction methods. In all samples the self-activated emission connected with donor-acceptor pairs VZn–D is found. Analysis of excitation spectra of this band shows that vacancy related defects are mainly localised in ZnCdSe wetting layer. It is found that increase of Se beam pressure results in: (i) the increase of the number of metal vacancy related defects and their appearance on nanoisland interface; (ii) enhancement of Cd/Zn interdiffusion process; (iii) the decrease of Cd content in nanoislands and suppression of nanoisland formation. It is proposed that observed transformation of nanoisland emission band is mainly caused by enhancement of interdiffusion process.