EFFECT OF COPPER DOPING ON THE STRUCTURAL AND OPTICAL PROPERTIES OF ZnO THIN FILMS PREPARED BY THERMAL EVAPORATION METHOD

In the work, the structures and the optical parameters were studied for ZnO and ZnO:Cu thin films which prepared by vacuum thermal evaporation deposition with different concentration of doping (2% and 4%). The X-Ray diffraction showed that ZnO, ZnO:Cu thin films which were prepared to have a polycrystalline hexagonal structure. The most preferential orientation is along the (002) direction for all deposited ZnO:Cu films. Some parameters of the films were calculated as the average grain size and the dislocation density. Optical properties measurement transmittance (T ) of the film shows that they have high transmittance (85.7%) is obtained for at copper concentration (4%). The optical properties such as absorption coefficient ( α ) and the extinction coefficient ( k ) was determined using the transmittance measurement from a UV-vis spectrophotometer, with a range of wavelength (300-1100) nm. And also calculated energy gap for thin films, the result has been shown that the optical energy gap decreases with increasing doping and reaches to low value of 3.13 eV with doping in of 4%.