화학공학소재연구정보센터
Applied Surface Science, Vol.257, No.24, 10551-10556, 2011
Characterization of ZnO-SnO2 thin film composites prepared by pulsed laser deposition
Thin films of ZnO-SnO2 composites have been deposited on Si(1 0 0) and glass substrates at 500 degrees C by pulsed laser ablation using different composite targets with ZnO amount varying between 1 and 50 wt%. The effect of increasing ZnO-content on electrical, optical and structural properties of the ZnO-SnO2 films has been investigated. X-ray diffraction analysis indicates that the as-deposited ZnO-SnO2 films can be both crystalline (for ZnO <1 wt%) and amorphous (for ZnO >= 10 wt%) in nature. Atomic force microscopy studies of the as-prepared composite films indicate that the surfaces are fairly smooth with rms roughness varying between 3.07 and 2.04 nm. The average optical transmittance of the as-deposited films in the visible range (400-800 nm), decreases from 90% to 72% for increasing ZnO concentration in the film. The band gap energy (E-g) seems to depend on the amount of ZnO addition, with the maximum obtained at 1 wt% ZnO. Assuming that the interband electron transition is direct, the optical band gap has been found to be in the range 3.24-3.69 eV for as-deposited composite films. The lowest electrical resistivity of 7.6 x 10(-3) Omega cm has been achieved with the 25 wt% ZnO composite film deposited at 500 degrees C. The photoluminescence spectrum of the composite films shows a decrease in PL intensity with increasing ZnO concentration. (C) 2011 Elsevier B.V. All rights reserved.