The effect of Al content, substrate temperature and nitrogen flow rate on optical band gap and optical features of nanostructured TiAlN thin films prepared by reactive magnetron sputtering

Abstract

In the present work, TiAlN thin films were prepared by using a dual reactive magnetron sputtering system on fused quartz substrates kept at room temperature and 400 °C; keeping nitrogen flow at 0.51 and 2.78 sccm, various DC and RF powers and the effect of these factors have been studied on the optical properties of the layers. The optical properties including absorption and transmission were studied by a UV–Visible spectrophotometer in the wavelength region (200–1100) nm. By plotting (αhν)2 and (αhν)1/2 versus the photon energy hυ, the optical band gap was evaluated. Experimental results show that layers with high percentage of aluminum and nitrogen have higher gap with respect to layers having high titanium percentage. TiAlN thin films deposited with 2.78 sccm nitrogen flow rate possess optical direct band gap in the range of 3.8–5.1 eV and optical indirect band gap in the range of 1.1–3.4 eV. The variation of optical band gap of the films that deposited on the substrate with 400 °C and nitrogen flow rate of 2.78 sccm was different from other layers.