DEPOSITION OF ZNO THIN-FILMS BY LASER-ABLATION

The c-axis oriented ZnO films are successfully grown at low substrate temperatures at a high deposition rate, using a KrF excimer laser ablation technique. The influences of substrate temperatures and N2O gas on the structures of the films obtained in a vacuum of 1.3 x 10(-3) Pa and a N2O atmosphere of 1.3 Pa are investigated. Species during laser ablation are also analyzed to discuss the characteristics of the films. The main results obtained are as follows. The films deposited on the glass at the substrate temperatures of 373-473 K show strong c-axis orientation at a rate of 1 nm/s. Grain sizes of the hexagonal films deposited on the Si (100) substrate are ranging from 4 to 40 nm. Good transparency for visible spectrum ranging from 80 to 85% is obtained with the films deposited in the N2O at the substrate temperatures of 473 approximately 573 K. These films are formed by depositing neutral atoms and ions following laser ablation. But the ZnO molecule does not deposit. In the low N2O pressure of 1.3 Pa, the kinetic energies of atoms and ions do not decrease so much to promote migration of atoms and grow the c-axis oriented transparent ZnO films at low substrate temperatures.