Highly conductive and transparent Ga-doped ZnO thin films deposited by chemical spray pyrolysis

Undoped and Ga doped ZnO thin films were deposited on borosilicate glass substrates via a simple but effective chemical spray pyrolysis technique. The samples were characterised by X-ray diffractometer, UV-vis spectrophotometry, Scanning electron microscopy and I-V measurements. The structural, morphological and optical properties were studied as a function of increasing Ga doping concentration from 0 to 7 at.%. XRD results revealed that the films were polycrystalline with hexagonal wurtzite crystal structure. Increasing Ga dopant concentration decreased the crystallite size from 74 to 19 nm whilst the band gap, dislocation density and lattice strain shifted to higher values. All the films exhibited high transmittance of about 85% in the entire visible spectral range. Lowest resistivity of 1.47 × 10−4 Ω cm was obtained at 3 at.% Ga concentration.