Morphological study of Sol-Gel derived ZnO:In thin films

This work presents morphological, structural and optical studies of ZnO and ZnO:In nanostructured thin films depending on In doping (four different concentrations). XRD study of 600°C annealed ZnO:In films reveals that crystallization strongly depends on indium concentration. The films are crystallized in wurtzite structure and only for the films with highest In addition, two crystal phases are detected wurtzite ZnO and cubic In
₂
O
₃
. The AFM investigation reveals that the lowest Root Mean Squared Roughness(RMS) is revealed for ZnO:In 0.5 film (15.96 nm) and the roughness increases up to 64.52 nm for ZnO:In 1. Columnar type structures can be observed in the AFM micrographs of the other two films - ZnO:In 2 and ZnO:In 3, as the columns vary in height and size. The effect of the indium doping into ZnO reveals changing of optical transmittance compared to ZnO film. The optical band gap of ZnO:In films, annealed at 600°C is in the range of 3.06-3.27 eV.