Impact of sputtering power on the properties of Al and Ga co-sputtered ZnO thin films

Abstract

In the current study three sets of Aluminum and Gallium co-sputtered Zinc Oxide films were grown with varying sputtering power (100, 200 and 300 W) on soda lime glass substrate using DC sputtering. Aluminum doped ZnO (Al2O3 2 wt%), Gallium doped ZnO (Ga2O3 2 wt%) sputtering targets were used. The thickness ratio of Al doped ZnO and Ga doped ZnO (1:1) was maintained same in all the Al and Ga co-sputtered (ZAG) thin films. Optical absorption data reveals the high transmission for the as grown films which achieved a maximum value of nearly 90 % in visible spectra for the 100 W deposited ZAG film. The XRD graph indicates a (002) preferred growth with other weak peaks at (102) and (103). This confirms the polycrystalline nature of the film. Intense peak is observed corresponding to (002) phase which implies a better crystallite size for the 300 W grown ZAG film. XRD results suggest that with increasing sputtering power the crystallite size shows an increasing trend. Hall Effect Measurement system was used to measure the electrical properties viz. carrier concentration, resistivity and mobility of the ZAG films. Lowest resistivity value of 5.46 × 10−4 Ω cm was obtained for the ZAG film deposited at sputtering power of 300 W. It was revealed from the obtained data with increasing sputtering power the resistivity value decreased and in the scale of 10−3 to 10−4 Ω cm with high optical transmittance. © 2015, Springer Science+Business Media New York.