dc and ac transport properties of Mn-doped ZnO thin films grown by pulsed laser ablation

MnxZn1−xO (x = 0.20) thin films were deposited on Pt coated Si substrates using pulsed laser ablation technique. The structural characteristics of the films were investigated by X-ray diffraction (XRD), while the dielectric response of the films was studied as a function of frequency and ambient temperature by employing impedance spectroscopy. It was found that all the films deposited on Pt coated Si substrates had c-axis preferred orientation perpendicular to the substrate, with full width at half maximum (FWHM) of the (0 0 2) X-ray reflection line being less than 0.5°. The dc and ac electrical conductivity of Mn-doped ZnO films were investigated as a function of temperature. The ac conductivity, σac(ω), varies as σac(ω) = Aωs with s in the range 0.4–0.9. The complex impedance plot showed data points lying on a single semicircle, implying the response originated from a single capacitive element corresponding to the bulk grains. The value of the activation energy computed from the Arrhenius plot of both dc and ac conductivities with 1000/T were 0.2 eV suggesting hopping conduction mechanism. The optical properties of Zn0.8Mn0.2O thin films were studied in the wavelength range 300–900 nm. The data were analyzed in the light of the existing theories and reflected a Burstein–Moss shift in these films. The films show magnetic properties, which are best described by a Curie–Weiss type behavior.