Thin tantalum and tantalum oxide films grown by pulsed laser deposition

The growth of tantalum and tantalum oxide films grown on Si (1 0 0) and qua rtz by 532 nm (Nd:YAG) pulsed laser deposition (PLD) in various O-2 gas env ironments has been investigated, Ellipsometry has been used to determine th e refractive index and thickness of the films whilst Fourier transform infr ared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and UV sp ectrophotometry were used to identify tantalum and tantalum oxide formation and optical transmittance as well as optical constants. The FTIR, XPS and UV spectra reveal a strong dependence of the film properties on the O-2 gas pressure used. The results showed that oxygen pressure could be used to co ntrol the composition of the films. XPS analysis showed that the compositio n of the layers changed from Ta2O5 to metal tantalum as the oxygen pressure was varied from 0.2 to 0.005 mbar. Under optimum deposition conditions, th e refractive index of the oxide layers was found to be around 2.10 +/- 0.05 which is close to the value of the bulk Ta2O5 of 2.2 while an optical tran smittance in the visible region of the spectrum up to 90% was obtained, The se properties compare very favourably with those of films produced by other techniques. (C) 2000 Elsevier Science B.V. All rights reserved.