Properties of ZnO thin films deposited by DC reactive magnetron sputtering under different plasma power

ZnO thin films were prepared by DC reactive magnetron sputtering under various values of the plasma power at room temperature. The samples were characterized with X-ray diffraction (XRD), optical transmittance, photoluminescence (PL), and atomic force microscopy (AFM), respectively. The results show that samples change from ZnO (110) dominant crystal orientation to ZnO (002) dominant crystal orientation with the increase of plasma power. The samples also exhibit compressive intrinsic stresses. The coherent domain size of the film crystallite along with the root mean square (RMS) of the surface roughness increases with the increase of the plasma power. Optical transmittance spectra reveal that all samples have excellent optical properties. With the increase of plasma power, slight optical transmittance decreasing and fundamental absorption edge red shifting were observed. Films prepared under higher plasma powers show weaker emission intensities, which may be related to substoichiometric composition.