Optical properties and current conduction in annealed (Ta2O5)0.94 – (TiO2)0.06 thin films. (October 2021) - Thapliyal, Prashant
Abstract: By sputtering the mosaic assembly of tantalum (Ta) and titanium (Ti) metal targets in the oxygen environment, (Ta2 O5 )1−x –(TiO2 )x, x = 0.06, thin films were deposited onto the quartz, and P/boron-silicon (1 0 0) substrates, at room temperature (RT). The RT deposited films were annealed for 1.5 h, from 500 to 800 °C. Formation of the crystal structure in the films was observed at and above 700 °C annealing. Optical transmittance data, measured with the UV–Vis spectrophotometer, were used to find out the extinction coefficient (k), refractive index (nopt ), and optical bandgap (Eg ) of the prepared films. With the increasing annealing temperature, both the nopt and Eg values were observed, decreasing from 2.218 to 2.160, and 4.23 to 4.02 eV, respectively. The extinction coefficient of amorphous films was observed lesser than the crystalline films. The current–voltage characteristics of the prepared film assisted metal–oxide–semiconductor (MOS) structures manifest different conductions, viz., ohmic at the lower electric fields; and Schottky, Poole–Frenkel, Fowler–Nordheim tunneling and space–charge–limited current, in the intermediate to higher fields, for different annealing treatments. Highlights: Prepared TTO0.06 thin films by reactive DC magnetron sputtering, and annealed at 500, 600, 700 and 800 °C. Measured refractive index, extinction coefficient, and optical band gap of the prepared TTO0.06 films. With the increasing annealing, both the nopt and Eg were decreased from 2.218 to 2.160 and 4.23 to 4.02 eV, respectively. The extinction coefficient of amorphous films was observed lesser than the crystalline films. Different conduction mechanisms were manifested from I–V characteristics.