Effect of base and oxygen partial pressures on the electrical and optical properties of indium molybdenum oxide thin films

Indium molybdenum oxide thin films were RF sputtered at room temperature on glass substrates with a reference base pressure of 7.5 × 10− 4 Pa. The electrical and optical properties of the films were studied as a function of oxygen partial pressures (OPP) ranging from 1.5 × 10− 3 Pa to 3.5 × 10− 3 Pa. The obtained data show that the bulk resistivity of the films increased by about 4 orders of magnitude (from 7.9 × 10− 3 to 7.6 × 101 Ω-cm) when the OPP increased from 1.5 × 10−3 to 3.5 × 10− 3 Pa, and the carrier concentration decreased by about 4 orders (from 1.77 × 1020 to 2.31 × 1016 cm− 3). On the other hand, the average visible transmittance of 30.54% of the films (brown colour; OPP = 1.5 × 10− 3 Pa) was increased with increasing OPP to a maximum of 80.47% (OPP = 3.5 × 10− 3 Pa). The optical band gap calculated from the absorption edge of the transmittance spectra ranges from 3.77 to 3.88 eV. Further, the optical and electrical properties of the films differ from those deposited at similar conditions but with a base pressure lower than 7.5 × 10− 4 Pa.