Applied Surface Science, Vol.254, No.4, 855-858, 2007
Excimer laser processing of ZnO thin films prepared by the sol-gel process
ZnO thin films were prepared on soda-lime glass from a single spin-coating deposition of a sol-gel prepared with anhydrous zinc acetate [Zn(C2H3O2)(2)], monoethanolamine [H2NC2H4OH] and isopropanol. The deposited films were dried at 50 and 300 degrees C. X-ray analysis showed that the films were amorphous. Laser annealing was performed using an excimer laser. The laser pulse repetition rate was 25 Hz with a pulse energy of 5.9 mJ, giving a fluence of 225 mJ cm(-2) on the ZnO film. Typically, five laser pulses per unit area of the film were used. After laser processing, the hexagonal wurtzite phase of zinc oxide was observed from X-ray diffraction pattern analysis. The thin films had a transparency of greater than 70% in the visible region. The optical band-gap energy was 3.454 eV. Scanning electron microscopy and profilometry analysis highlighted the change in morphology that occurred as a result of laser processing. This comparative study shows that our sol-gel processing route differs significantly from ZnO sol-gel films prepared by conventional furnace annealing which requires temperatures above 450 degrees C for the formation of crystalline ZnO. (c) 2007 Elsevier B.V. All rights reserved.