Effect of Al-doped on physical properties of ZnO Thin films grown by spray pyrolysis on SnO2: F/glass

Transparent conducting thin films of aluminum-doped zinc oxide (ZnO:Al) have been deposited on SnO2:F/glass by the chemical spray technique, starting from zinc acetate (CH3CO2)(2)Zn center dot 2H(2)O and aluminum chloride AlCl3. The effect of changing the aluminum-to-zinc ratio y from 0 to 3 at.%, has been thoroughly investigated. It was found that the optical and electrical properties of Al doped ZnO films improved with the addition of aluminum in the spray solution until y=2%. At this Al doping percentage, the thin layers have a resistivity equal to 4.1 x 10(-4) Omega.cm and a transmittance of about 90 % in the region [600-1000] nm. XRD patterns confirm that the films have polycristalline nature and a wurtzite (hexagonal) structure which characterized with (100), (002) and (101) principal orientations. The undoped films have (002) as the preferred orientation but Al doped ones have (101) as the preferred orientation. Beyond y=1%, peak intensities decrease considerably.