Optical evidences of ZnS0.78Te0.22 quantum dots formed in ZnTe matrix

Thin ZnS0.78Te0.22 layers embedded in ZnTe matrix have been grown on GaAs (1 0 0) substrate by hot-wall epitaxy technique with varying growth time. Their optical properties have been investigated by photoluminescence (PL) measurements at low temperature and by temperature-dependent PL measurements. PL measurements show that the quantum dots (QDs) related peak at lower energy side with a broad full-widths at half-maximum (FWHM) and the two-dimensional (2D) layer related peak at higher energy side with a narrow FWHM are clearly resolved and their energies shift to lower energies as the ZnS0.78Te0.22 growth time increases. It is also found from temperature-dependent PL measurements that the activation energy of QDs is almost two times larger than that of 2D layer. Atomic force microscopy confirms their quantum dot formation.