Effect on Al2O3 doping concentration of RF magnetron sputtered ZnO:Al films for solar cell applications

Al-doped ZnO (AZO) films were deposited onto glass substrates by RF magnetron sputtering for solar cell applications. The effects of the Al2O3 doping concentration oil the structural, electrical, and optical properties of the AZO films were investigated. As the Al2O3 doping concentration was increased to 4.0 wt %. X-ray diffraction (XRD) showed a deterioration in the (002) peak intensity and a shift towards a higher angle. The best electrical properties (p = 9.8 X 10(-4) Omega cm, mu(H=) 22 cm(2) V-1 s(-1), and n(e) = 2.89 x 10(20)cm(-3)) were obtained in the AZO sample containing 2 wt% Al2O3 transmission >83% in the visible ran,,e was also observed and the optical bandgap was increased to 3.63eV at an Al2O3 concentration of 4 wt %. For photoluminescence (PL) spectra. one UV emission peak at approximately 3.2 eV and it broad peak in the visible range from 2.3 to 2.7eV were observed at Al2O3 doping concentrations ranging from 0-2.0w1. Blue emission at 2.67 eV, which indicates a non-stoichiometric structure, was only observed in the 4 wt % doped AZO films.