Thermal Treatment for Elimination of Impurities in ZnO Thin Films

We investigated the photoluminescence of ZnO sol-gel films coated on glass substrates using a spincoating method and then annealed in temperatures ranging from 230 • C to 600 • C. The primary purpose of the heat treatment was the elimination of organic waste products and polycrystalline layer formation.The temperature dependence of photoluminescence was investigated.Gaussian deconvolution was performed for measurements done in T = 12 K.This procedure provides insights into optically active defects formed in the material.The method of the Gaussian deconvolution was discussed, along with information regarding the control of fitting parameters and a comparison between different spectra.We demonstrated that luminescence properties could be tuned by changing the annealing conditions of deposited sol-gel films.Moreover, the positions of the emission peaks were discussed concerning specific defects such as vacancies or interstitials.In addition, organic waste products remain in a batch after the synthesis can be transferred to the glass substrate.Obtained ZnO films show significant differences in emission spectra associated with hydrogen, carbon, and nitrogen impurities elimination.Higher temperatures and longer annealing times benefit exciton emissions, linked with improved crystallinity of films.