Role of hydrogen treatment on microstructural and opto-electrical properties of amorphous ITO thin films deposited by reactive gas-timing DC magnetron sputtering

Abstract

Hydrogenated amorphous indium-tin-oxide (ITO) thin films have been prepared using reactive gas-timing DC magnetron sputtering technique, onto externally unheated glass substrate and without any heat treatment. In order to study the effect of hydrogen on the microstructural and optoelectrical properties of the ITO films, an additional hydrogen input line is added to the sputtering system and the hydrogen partial flow rate in the plasma gas mixture is varied over the range 0–0.9 sccm, while the other sputtering parameters are kept constant and optimized during the film growth. The optimized parameters are found to be 100 W DC power, 25 mTorr working pressure, and 7 cm electrode spacing. Introduction of the reactive hydrogen into the deposition chamber is achieved using uniform and step profiles. Characterization of the deposited hydrogenated amorphous ITO thin films are made using X-ray diffraction (XRD), atomic force microscopy (AFM), four probe electrical conductivity, photoluminescence (PL), and UV–Visible spectroscopy. A minimum sheet resistance of 8.34 $\Omega$/square, transmittance of 81.6% with a Haackes figure of merit of $15.7 \times {10^{ - 3}}$ ${\Omega ^{ - 1}}$, thickness of 380 nm, and optical band gap of 4.02 eV are obtained for the hydrogenated thin film prepared by uniform introducing profile of hydrogen reactive gas at 0.1 sccm hydrogen flow rate.