Photo-excited photonic characteristics of ZnO thin films deposited by laser ablation method

Zinc oxide (ZnO), having a wide direct band gap of 3.37 eV at room temperature, may be a new potential candidate for optoelectronic devices such as ultraviolet (UV) laser, blue light-emitting diode, and phosphorescent display. We have studied the ZnO thin films deposited by the pulsed laser ablation (PLA) method. In order to prepare high-quality ZnO thin films, the spectroscopic properties of the plasma plume produced during film deposition were investigated to correlate the properties of the deposited film with plasma characteristics. Furthermore, we have deposited the ZnO thin films at various deposition conditions such as ambient oxygen gas pressure, substrate material, and substrate temperature. We have investigated the effect of deposition conditions on structural and optical properties of the ZnO thin films. X-ray diffraction, atomic force microscopy, UV-visible photometry, and photoluminescence measurements were used to characterize the grown films. The ZnO thin films deposited at ambient oxygen gas pressure of 5 mTorr and substrate temperature of 550 °C showed strong c-axis (002) orientation. The ZnO thin film deposited on Al₂O₃ (0001) at these deposition conditions provided the UV-stimulated emission around 395 nm.