Ss. Camargo et al., STRUCTURAL MODIFICATIONS AND TEMPERATURE STABILITY OF SILICON INCORPORATED DIAMOND-LIKE A-C-H FILMS, Thin solid films, 332(1-2), 1998, pp. 130-135
Thermal stability of diamond-like carbon is still a problem which limi
ts the potential applications of this material. With the aim of obtain
ing a material with increased stability, the behaviour of silicon inco
rporated hydrogenated amorphous carbon films (a-C1-xSix:H) under therm
al annealing was investigated. Results show that the observed effects
can be divided in two groups: low temperature (T < 400 degrees C) and
high temperature (T > 400 degrees C) effects. In contrast to what is o
bserved in case of pure a-C:H, several of the properties of the films
were found to change in the low temperature range. A detailed analysis
of the infrared absorption spectra showed that the density of sp(3) C
-H bonds is increased while the olefinic sp(2) ones are reduced by ann
ealing. A shift of the Si-H stretching mode to lower wavenumbers is al
so observed, indicating that void elimination may occur due to bond re
construction. In this way, a material with reduced spin density, small
er residual stress and increased optical gap results, indicating an in
creased polymeric character. Upon annealing in the high temperature ra
nge, the material degradation processes of hydrogen loss and graphitiz
ation start to occur. In the case of films with low silicon content: t
he hydrogen effusion process is associated to the graphitization of th
e material. As the silicon content is increased, hydrogen effusion is
shifted to higher temperatures and graphitization is inhibited due to
the increased disorder presented by these films. (C) 1998 Elsevier Sci
ence S.A. All rights reserved.