Photoluminescence and Optically Pumped Ultraviolet Lasing from Nanocrystalline ZnO Thin Films Prepared by Thermal Oxidation of High-Quality ZnS Thin Films

摘要: We present a simple and useful method for preparing high-quality nanocrystalline ZnO thin films, i.e. the thermal oxidation of ZnS films prepared by low-pressure metal-organic chemical vapour deposition technique. The x-ray diffraction measurements reveal that has hexagonal wurtzite structure. Raman spectra show longitudinal optical phonon with E1-mode appears at 578 cm-1. multiple scattering process is also observed, indicating formation film. photoluminescence spectrum single emission peak 3.264 eV from free-exciton mission, under condition low excitation power room temperature. However, when intensities exceed threshold 150 kW/cm2, new narrow emerges lower energies, which are attributed to exciton-exciton collisions, called P line. intensity this increases superlinearly pumping over value. This supplies strong evidence stimulated emission. cavity modes observed in indicate successful realization optically pumped lasing