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.