Optical and Electrical Properties of Silver-Doped Zinc Oxide Films

The optical and electrical properties of silver-doped ZnO (AgZnO) films with Ag concentrations of 0.05 and 0.24 at % were analyzed using XRD, EDS, resistance, transmittance and reflectance measurements. The 0.05 at % AgZnO and as-deposited 0.24 at % AgZnO films exhibited n-type doping, whereas the annealed 0.24 at % AgZnO films showed p-type doping. The crystallite sizes of the 0.05 and 0.24 at % AgZnO films were 24 and 28 nm. The redshift of the band gap was 0.02 eV for 0.24 at % AgZnO. The sample with 0.24 at % Ag exhibits a polaron features in the range 900–3700 cm–1, and demonstrated a paramagnetic-to-diamagnetic transition. The 0.05 at % AgZnO film showed a negative temperature coefficient of resistivity. These findings suggest that a 0.24 at % Ag concentration is favorable for achieving p-type doping in ZnO and for the formation of polarons, whereas the 0.05 at % AgZnO film could be used for thermal sensing applications.