Laser Raman and X-ray photoelectron spectroscopy of phosphorus containing diamond-like carbon films grown by pulsed laser ablation methods

Mechanically hard, electrically conducting diamond-like carbon (DLC) films containing 0 to similar to 26 at.% phosphorus have been deposited on both Si and quartz substrates by pulsed laser ablation of graphite/phosphorus targets (containing varying percentages of phosphorus), at a range of substrate temperatures (T-sub = 25-400 degreesC), in vacuum. Laser Raman spectra (514.5 nm excitation wavelength) of the as-deposited films yield the band maxima and relative intensities of the D and G peaks (I(D) and I(G), respectively), as a function of T-sub P:C ratio and incident laser fluence, F. Nanocrystalline graphitisation was deduced to occur at higher substrate temperatures, consistent with previous results for undoped DLC and CNx, films. P containing DLC films deposited at lower T-sub values exhibit higher I(D)/I(G) ratios than the corresponding undoped DLC films. Measured trends in G-peak positions and I(D)/I(G) ratios are consistent with values for the C-sp(3) content obtained by deconvoluting the C 1s peak in the corresponding X-ray photoelectron spectra. XPS also reveals a decrease in P content in films grown at higher T-sub and at higher F, suggesting that P atoms are more mobile than C atoms, and thus less strongly accommodated, during the film growth process. (C) 2003 Elsevier B.V All rights reserved.