Correlation between hydrogen content and structure of pulsed laser deposited carbon nitride films

Carbon nitride films fabricated by ablating a graphite target in an N-2 atm osphere possess a high affinity for hydrogen incorporation. The differences in both the absolute values and the depth distribution of hydrogen within the films correlate well with changes in mass density. The dense films, dep osited at and below 5 Pa N-2 pressure, contain 1.6-3.4 at.% hydrogen with t wo maxima in the depth distribution, namely one near the surface and anothe r one at the substrate-film interface, suggesting both in situ and ex situ incorporation. Significantly higher hydrogen contents (12.8-16.45 at.%) uni formly distributed throughout the whole thickness characterize the less den se films grown in the 50-100-Pa pressure domain. These films are hydrogenat ed ex situ as a consequence of the penetration of hydrogen from the atmosph eric air through their open structure. The hydrogen content of the unintent ionally hydrogenated carbon nitride films is a sensitive indicator of the c hanges in film microstructure. (C) 2001 Elsevier Science B.V. All rights re served.