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FIZIKA A 8 (1999) 3 , 131-140
 
STRUCTURAL PROPERTIES OF a-Si1-xCx:H BY SAXS AND
IR SPECTROSCOPY
DAVOR GRACIN and PAVO
DUBČEK
"R. Bošković" Institute, POB 1016, Bijenička 54, 10000
Zagreb, Croatia
Dedicated to Professor Boran Leontić on the occasion of his 70th
birthday
Received 19 November 1999; revised manuscript received 2 February 2000
Accepted 28 February 2000
The a-Si1-xCx:H thin films, with carbon concentrations up to x =
0.3 deposited by means of a DC magnetron sputtering source, using benzene vapour as the
origin of carbon atoms, were analysed by small-angle X-ray scattering (SAXS) and IR
spectroscopy. The incorporation of carbon atoms in a-Si:H results in the appearance of IR
absorption related to the Si-C and C-H bonds and a slight decrease of absorption related
to Si-H bonds. By increasing the carbon concentration, stretching frequency of Si-H bonds
increases. This frequency, which is related to the described changes, is considered to be
the consequence of an increasing void volume ratio and/or void volume per each Si-H
oscillator. The SAXS data of pure a-Si:H indicate ``particles" with the giro radius RG
= 1.27 nm, which increases with the carbon content up to RG = 2.05 nm. These
``particles" are attributed to the clusters of small voids with dimensions up to
several silicon vacancies.
PACS numbers: 87.15.Rn, 87.50.-a
UDC 535.217, 539.21
Keywords: a-Si1-xCx:H thin films, different carbon
concentrations, DC magnetron sputtering, small angle X-ray scattering (SAXS), IR
spectroscopy, stretching frequency of Si-H bonds, clusters of small voids
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