Changes in electrical and structural properties of indium oxide thin films through post-deposition annealing

The annealing effects on the electrical properties and microstructures of indium oxide (In2O3) thin films were investigated. The In2O3 thin films with the thickness of about 150 nm were annealed at various temperatures ranging from 100 to 600 deg. C in air after the sputtering deposition. It was found that the carrier density of the In2O3 thin films decreased with increasing in the annealing temperature and then started to increase at a certain temperature. This indicated that the reduction of the In2O3 thin films was promoted at high annealing temperature. The Hall mobility of the In2O3 thin films increased through the reduction; furthermore, the d-spacing of the In2O3 crystal lattice plane tended toward ideal value. It can be believed from these results that one of the principal electron scattering in the In2O3 thin films is attributed to excess oxygen atoms that expand the d-spacing.