ZnS/Si composite nano-structured thin films and their photoluminescence

Abstract

Thin films of ZnS/Si composite were prepared using pulsed laser deposition by alternately ablating ZnS and Si materials on a rotary target holder onto an ultra-clean glass substrate in vacuum. The film structure consisted of a mixture of Si and ZnS nanocrystals with some segregation of S and Zn. Most of the particles in the film were found to be less than 15 nm in diameter even after annealing for 6 hours at 500°C in air. With excitation wavelengths of 280 nm and 380 nm, the composite film yielded largely independent photoluminescent (PL) emission peaks originating from the Si and ZnS nanoparticles. There is a slight difference in the Si and ZnS PL results compared with those obtained from thin films of Si nanocrystals and ZnS nanoparticles embedded in SiO2 matrices. This difference is attributed to the different segregation and oxidation behaviors of the materials in different neighborhood environments. Our results open up the possibility of modifying the PL of ZnS/Si composite films for potential applications in multiple-function optoelectronic devices. © 2006 IOP Publishing Ltd.