Effect of oxygen pressure on optical properties of Cu-doped ZnO thin films prepared by PLD

In order to study the effect of oxygen pressure on the structure and optical property of ZnO thin films, different Cu-doped ZnO thin films were prepared on P-Si〈111〉 substrates by means of pulsed laser deposition (PLD) technique. The structures of the specimens were analyzed with X-ray diffraction(XRD)and their photoluminescence spectra were measured with a fluorescent spectrophotometer. XRD patterns indicate all the specimens prepared under the conditions of 400℃ substrate temperature and 0.2Pa oxygen pressure have a strong diffraction peak and high preferential orientation in the (002) crystallographic direction，but the diffraction peak of Cu doesn't appear. Results at room temperature showed that each of the samples had a blue band at about 460nm (2.71eV).The blue emission is attributed to the transition of electrons from the bottom of conduction band to zinc vacancy or from zinc interstitial to the top of valence band. The photoluminescence intensity of the emission luminescence increases as the oxygen pressure increases.