Preparation of ZnO films using metallic Zinc thin layers: the effect of oxidation temperature and substrate type

In this study, the effect of oxidation temperature and substrate type on the morphology and optical properties of the ZnO films were investigated. The films were prepared by oxidation of metallic zinc layer under air atmosphere. To examine the effect of oxidation on the growth process, the temperatures of 400, 600, and 800 C were considered. To study the impact of the substrate, amorphous quartz and crystalline silicon substrates were used. At 400 C and quartz substrate, the thin layer grows in the form of particles, while it grows in the nanoflake-like shape when using silicon substrate. The surface roughness increases by the increasing the oxidation temperature. The samples prepared on silicon substrate indicate higher surface roughness than those prepared using quartz substrate. The band gap energy of the films elevated by increasing the oxidation temperature from 400 to 600 C, and then decreased by further increasing the annealing temperature to 800 C. The photoluminescence (PL) spectra of the films confirmed the emission due to exciton recombination related to near band edge emission (NBE) and emission due to defects.