Role of growth parameters on structural and optical properties of ZnS nanocluster thin films grown by solution growth technique

In this study, the nanosized ZnS thin films that can be used for fabrication of blue light-emitting diodes, electro-optic modulators, and n-window layers of solar cells were grown by the solution growth technique (SGT), and their structural and optical properties were examined. Based on the results obtained, the quantum size effects of ZnS were systematically investigated. Governing factors related to the growth condition were the concentration of precursor solution, growth temperature, concentration of aq. ammonia and growth duration. X-ray diffraction patterns showed that the ZnS thin film obtained in this study had the cubic structure (beta-ZnS). With decreasing growth temperature and decreasing concentration of precursor solution, the surface morphology of film was found to improve. In particular, this is the first time that the surface morphology dependence of ZnS film grown by SGT on the ammonia concentration is reported. The energy band gaps of samples were determined from the optical transmittance values, and were shown to vary from 3.69 to 3.91 eV. These values were substantially higher than 3.65 eV of bulk ZnS demonstrating that the quantum size effect of SGT grown ZnS is remarkable. (C) 2002 Published by Elsevier Science B.V.