Phase transitions from semiconductive amorphous to conductive poly crystal line in indium silicon oxide thin films

摘要

The enhancement in electrical conductivity and optical transparency induced by a phase transition from amorphous to polycrystalline in lightly silicon-doped indium oxide (InSiO) thin films is studied. The phase transition caused by simple thermal annealing transforms the InSiO thin films from semiconductors to conductors. Silicon atoms form SiO_4 tetrahedra in InSiO, which enhances the overlap of In 5s orbitals as a result of the distortion of InO_6 octahedral networks. Desorption of weakly bonded oxygen releases electrons from deep subgap states and enhances the electrical conductivity and optical transparency of the films. Optical absorption and X-ray photoelectron spec-troscopy measurements reveal that the phase transition causes a Fermi energy shift of ～0.2 eV.