Crystallization process and electro-optical properties of In2O3 and ITO thin films

Abstract

Amorphous indium oxide (In2O3) and 10-wt% SnO2 doped In2O3 (ITO) thin films were prepared by pulsed-laser deposition. These films were crystallized upon heating in vacuum at an effective heating rate of 0.00847°C/s, while the evolution of the structure was observed by in situ X-ray diffraction measurements. Fast crystallization of the films is observed in the temperature ranges 165–210°C and 185–230°C for the In2O3 and ITO films, respectively. The crystallization kinetics is described by a reaction equation, with activation energies of 2.31±0.06eV and 2.41eV and order of reactions of 0.75±0.07 and 0.75 for the In2O3 and ITO films, respectively. The structures of the films observed here during heating are compared with those obtained upon film growth at different temperatures. The resistivity of the films depends on the evolution of the structure, the oxygen content and the activation of tin dopants in the films. A low resistivity of 5.5×10−4Ωcm was obtained for the In2O3 and ITO films at room temperature, after annealing to 250°C the resistivity of the ITO film reduces to 1.2×10−4Ωcm.