Role of Si Incorporation on the Transparent Conducting Properties of In2O3 Thin Films

Abstract

Thin films of indium oxide (In2O3) incorporated with Si ion impurities were prepared on glass substrates by a vacuum evaporation technique. The influence of the Si inclusion on the structural and optical properties of the host In2O3 films was analytically studied by the Rietveld refinement method. It was observed that the insertion of Si ion-species into In2O3 lattice did not change its bixbyite phase. However, a gradual deterioration of crystalline structure with increasing of Si inclusion in the films sample was observed. The optical measurements revealed that the band gap of host In2O3 films blue-shifted by the inclusion of Si ions, which was ascribed to the Moss-Burstein effect. The transparent conducting properties of the films (conductivity, carrier mobility and concentration) were extracted from optical measurements, and compared with the known conduction parameters measured by a direct electrical method. The electrical conductivity, carrier concentration and optical transparency of host In2O3 films were improved with Si incorporation for concentrations less than ∼ 16 at.%. However, Si-incorporation decreased the carrier mobility. For Si inclusion of ∼ 16 at.%, In2O3:Si film shows a resistivity of 3.73 × 10−3 Ω cm and an optical transparency of ∼ 90%, which are acceptable values for the fabrication of different types of photovoltaics.