Ultraviolet annealing of thin films grown by pulsed laser deposition

In this paper, we report the results of ultraviolet (UV) annealing of tanta lum oxide and tantalum films deposited on Si (100) and quartz by pulsed las er deposition (PLD). The effects of annealing pressure and time on the stru ctural and optical properties have been studied. Ellipsometry was used to d etermine the refractive index and thickness of the films, while Fourier tra nsform infrared spectroscopy (FTIR) and UV spectrophotometry were used to i dentify tantalum pentoxide (Ta2O5) formation and determine the optical band gap and transmittance. The FTIR and UV spectra reveal a strong dependence of the film properties on the annealing: parameters used with pressure bein g the most sensitive. Under optimum annealing conditions, the refractive in dex of the layers was found to be around 2.18 which is close to the value o f the bulk Ta2O5 of 2.2, while an optical band gap of 4.2 eV and an optical transmittance in the visible region of the spectrum greater than 85% were obtained, which compare very favourably with films produced by other techni ques. (C) 2000 Published by Elsevier Science B.V. All rights reserved.