PHOTOLUMINESCENCE AND CATHODOLUMINESCENCE OF ZNSSE QUANTUM-WELL HETEROSTRUCTURES GROWN BY MOVPE

Lateral- and depth-resolved cathodoluminescence as well as photolumine scence of MOVPE-grown single- and multi quantum well ZnSSe-based heter ostructures in the temperature range of 14-300 K were investigated. Th e intensity ratios between different emission peaks and their dependen cies on the electron penetration depth together with the temperature d ependence of photoluminescence spectra permit concluding that the tran sport of non-equilibrium carriers or excitons in the structure is hind ered by potential fluctuations created by microvariations of the sulph ur content. The deep centres are localized mostly in the near-substrat e region which is indicated by an increase of the self-activated emiss ion at 2.2 eV with increasing electron beam penetration depth. Further improvement of layer homogeneity as well as a sufficient distance bet ween the quantum well and the substrate together with minimization of the interlayer strain is necessary to improve the radiative properties of ZnSe-based heterostructures.