Grain-size effect on the electrical properties of nanocrystalline indium tin oxide thin films

•Nanometer-sized small grains were observed in the ITO thin films.•The grain size increased as the post-thermal annealing temperature increased.•The mobility of ITO thin films increased with increasing grain size.•The ITO film annealed at 300°C was an amorphous phase, while the others were polycrystalline structure.