Photoluminescence characterization of ZnCdSe/ZnSe quantum dot systems with different ZnCdSe coverages

We have characterized the temperature and excitation power density dependence of the photoluminescence (PL) spectra from ZnCdSe/ZnSe quantum dot (QD) system with different ZnCdSe coverages. A single spectral peak was observed from the sample composed of thick ZnCdSe layers while two peaks were observed from those with thin ZnCdSe layers. The temperature dependence of the peak position and width indicated that the spectral features originated from three-dimensionally confined QD systems. The relative intensity of spectral peaks remained the same even when the excitation power density was 80-fold weaker, and verified that different spectral lines originated from different groups of QDs instead of emissions from different excited states within one group of QDs. The thickness variation of spectral profiles also characterized the growth-mode evolution with the ZnCdSe thickness.