LASER ANNEALING OF ZINC-OXIDE THIN-FILM DEPOSITED BY SPRAY-CVD

A polycrystalline ZnO film was deposited on quartz and silicon substra tes by a spray-CVD method. The deposited film was annealed by thermal and by laser heating. Both CW CO2 laser and pulsed excimer (XeCl) lase rs were used for the purpose. The as-grown film and the annealed film were analysed for crystallinity and compositions by XRD, for surface m orphology by SEM, for band gap by optical absorption and for electrica l parameters by Van der Pauw and Wall effect measurements. While the e xcimer laser annealing improved the crystallinity with higher laser po wer density, CW CO2 laser incorporated the crystallinity only at low p ower. High power CO2 laser annealing damaged the ZnO surface with the creation of more defects. This was verified by SEM morphology studies. There was no change in band gap which ensures no formation of any oth er phase in ZnO due to annealing effects. The increase in resistivity both by thermal and pulsed laser annealing was confirmed by Van der Pa nw resistivity measurements. The majority carrier concentration and mo bility were determined by Hall effect measurements. (C) 1998 Elsevier Science S.A. All rights reserved.