Enhanced electrical properties of ZnO transparent conducting films prepared by electron beam annealing

Pure ZnO precursor films were prepared by a sol-gel spin coating method. The films were directly annealed by the electron beam (EB) for 5 min. The structural, optical and electrical properties were investigated by means of SEM, AFM, XRD, UV-vis spectrophotometer and Hall-effect measurement. SEM and AFM studies revealed smooth, dense film microstructure with some holes. The average grain size ranged from 10 nm to 60 nm and the surface RMS roughness of the films is less than 3 nm. X-rays diffraction patterns showed (002) preferential growth in all annealed films. From optical transmittance spectra, the absorption edge of the films was determined to be at ∼380 nm with > 85% transmittance in visible region. ZnO film annealed with beam current 0.7 mA was found to exhibit minimum resistivity value of 1.57 × 10−2 Ωcm and carrier concentration as high as 6.37 × 1019 cm−3, which is 2 ∼ 3 orders better than that of the typical pure ZnO thin films using sol-gel method.