Some studies on Molybdenum doped Indium oxide thin films rf sputtered at room temperature

Abstract

Thin films of molybdenum doped indium oxide (IMO) were rf sputtered onto glass substrates at room temperature. The films were studied as a function of oxygen volume percentage (OVP) ranging 1.4 - 10.0 in the sputtering chamber. The thickness of the films found varying between 180 and 260 nm. The X-ray diffraction pattern showed the films are polycrystalline with the peaks corresponding to (222) and (400) planes and one among them showing as a preferential orientation. It is observed that the preferred orientation changes from (222) plane to (400) as the OVP increases from 1.4 to 10.0 %. The transmittance spectra were found to be in the range of 77 to 89 %. The optical band gap calculated from the absorption coefficient of transmittance spectra was around 3.9 eV. The negative sign of Hall coefficient confirmed the films were n-type conducting. The bulk resistivity increased from 2.26 × 10⁻³ to 4.08 × 10⁻¹ Ω−cm for the increase in OVP from 1.4 to 4.1 %, and thereafter increased dramatically so as the Hall coefficients were not detectable. From the AFM morphologies it is evaluated that the RMS roughness of the films ranges from 0.9 to 3.2 nm.