ZnSe nanocrystals obtained in pores of SiO2 matrix with temperature stable green luminescence

ZnSe nanocrystals have been obtained in the pores of SiO2 matrices by two different methods - chemical vapour deposition (CVD) method and method of impregnation of SiO2 matrices with ZnCl2 solution and subsequent annealing in H2Se atmosphere. Luminescence spectra of ZnSe nanocrystals are characterized by wide green band which intensity remains equally high as at 77 K, so at 300 K contrary to ZnSe bulk crystal in which intensity of this band drops almost to zero at temperatures above 150 K. Analyses of temperature dependences of luminescence spectra and decay curves have shown that the quenching of the green band in bulk and nanocrystals occurs via different mechanisms - while for bulk crystals quenching takes place with participation of the bottom of conduction band (CB), for nanocrystals this mechanism becomes ineffective due to sufficient blueshift of the bottom of CB determined by quantum size effect and quenching is restricted to direct energy transfer to nonradiative defect sites of nanocrystal.