[Zhang, Rengang] Wuhan Univ Sci & Technol, Dept Appl Phys, Wuhan 430081, Peoples R China
; [Wang, Baoyi
; Wei, Long] Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China
Nanocrystalline ZnS thin films are prepared on glass and quartz substrates by sulfurizing ZnO thin films in the H2S-containing mixture at 500 degrees C. These films are investigated by X-ray diffraction, scanning electron morphology, optical transmittance and photoluminescence spectra. The results show that the ZnS thin films have the hexagonal structure with a c-axis preferred orientation. Also, these nanostructure ZnS thin films with the grain size of similar to 50 nm along the c-axis, exhibit the optical transparency as high as similar to 80% in the visible region. It is found that sulfur replacement of oxygen sites in crystal lattices and recrystallization can take place during sulfidation, resulting in an evident increase of the grain size for the sulfurized films. Under the optimum sulfidation time of 2 h, the resultant ZnS thin films have a high crystallinity, low defect concentration and good optical properties with the band gap of 3.66 eV. (C) 2008 Elsevier Ltd. All rights reserved.