Influence of deposition parameters on ZnO and ZnO:Al thin films

Abstract

Zinc oxide (ZnO) and 2% aluminium doped ZnO (ZnO: Al) thin films were deposited on glass by using r. f. magnetron sputtering without intentional heating. The r. f. power was varied in the range of 150 W to 175 W and process gas (argon) pressure was changed from 0.20 Pa to 0.60 Pa in small variation ranges to identify the influence of sputtering parameters. Achieved results were analysed with the help of XRD, AFM, SEM, HRTEM, four point probe, optical transmittance measurement techniques. According to the results, 165 W was selected as optimum r. f. power value, while 0.20 Pa for ZnO and 0.30 Pa for ZnO:Al thin films were determined as argon gas pressure values. All the thin films were oriented with the crystallographic c-(002) axis perpendicular to the substrate surface. Moreover, at this deposition values; the resistivity was measured as around 10(-3) Omega. cm, while the deposition rate showed variations. The optical transmittance of ZnO: Al was obtained (85%) higher than ZnO (75%) thin film. The optical band gap was changed from 3.45 eV to 4.2 eV. Surface roughness (RMS) values were obtained as 5.44 nm for ZnO and as 2.36 nm for ZnO: Al. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim