Structural, morphological, optical and electrical evolution of spray deposited ZnO rods co-doped with indium and sulphur atoms

Undoped and (In–S) co-doped ZnO films were grown by the spray pyrolysis method on glass substrates. The structural, morphological, optical and electrical properties of all the samples were studied in detail. X-ray diffraction results showed that all the samples have a hexagonal wurtzite structure with the preferred orientation that changed from (002) to the random orientation after (In–S) co-doping. From the scanning electron microscopy analysis, it is noted that the morphology of ZnO changed from rods to thin film upon (In–S) co-doping. Compared to undoped ZnO rods, transparency of (In–S) co-doped ZnO thin films significantly increased whereas their band gap values gradually decreased. From photoluminescence measurements, it is observed that the UV peak completely quenched after (In–S) co-doping while the deep level band intensity slightly increased especially for 2 and 4 at.% (In, S) co-doped ZnO samples. Compared with undoped sample, the carrier concentration enhanced with the increase of (In–S) co-doping to 4 at.% and further increase in the co-doping amount results in the decline of the conductivity.