Deposition of the low resistive Ag–N dual acceptor doped p-type ZnO thin films

Nanocrystalline Ag and N dual-acceptor doped zinc oxide (ZnO:(Ag, N)) films were deposited on glass substrates by the spray pyrolysis technique. The Hall measurement, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), UV–vis and luminescence spectroscopy techniques were employed to investigate the electrical, structural, morphological and optical properties of the films in detail as a function of concentration of dopants. The atomic force microscopy (AFM) technique was employed to study the surface roughness and 3D surface profiles of the films. The Hall measurement results showed that all the ZnO:(Ag, N) films exhibited p-type conduction. The films with a doping concentration of 4 at% is found to show the lowest resistivity of 8.70×10−2 Ω cm and highest carrier concentration of 2.17×1018 cm−3. The XRD results revealed that all the films have good crystalline quality with a preferential c-axis orientation. The SEM micrographs of all the films exhibited uniformly distributed spherical grains over the surface of the films. The EDX and elemental mapping results showed the presence and distribution of Zn, O, Ag and N in the deposited films. The as-deposited ZnO:(Ag, N) films showed an average transmittance of about 90% in the visible region. The photoluminescence (PL) results suggested the suppression of native defect levels due to the incorporation of Ag and N in to the ZnO films.