IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Thin Films Friday Sessions
       Session TF-FrM

Paper TF-FrM10
The Investigation of Homogeneity of a-SiC:H Thin Films

Friday, November 2, 2001, 11:20 am, Room 123

Session: Diamond and Related Materials
Presenter: A.A. Sherchenkov, Moscow Inst. of Electronic Technology, Russian Federation
Authors: B.G. Budaguan, Moscow Inst. of Electronic Technology, Russian Federation
A.A. Sherchenkov, Moscow Inst. of Electronic Technology, Russian Federation
E.I. Artemov, Moscow Inst. of Electronic Technology, Russian Federation
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Hydrogenated amorphous silicon-carbon alloy (a-SiC:H)is an important material for device applications because of the possibility to control the optical bandgap by changing the carbon concentration. The physical properties and stability of a-SiC:H as well as device quality strongly depend on material's structural properties and, particularly, on its structural homogeneity. In this paper we determine the local chemical environment of the Si-H bond and the forms of carbon incorporation by analysing with use of chemical induction model the dependence of the Si-H stretching frequency shift on the alloy composition r=[C]/[Si]. a-SiC:H thin films were prepared by decomposition in the low frequency (55 kHz) glow-discharge plasma the gases mixture of silane and methane with varying methane fraction at substrate temperature of 320°C. Si and C atoms can be backbonded to Si-H bond in four possible ways to form HSiSi@sub 3-n@C@sub n@ configurations with n=0-3. So we decomposed the IR absorption band between 1840 and 2300 cm@super -1@ attributed to the Si-H stretching vibrations in monohydride SiH group into four subbands with Gauss distributions. Using the chemical induction model we calculated the dependencies of frequencies for each of four peaks both on the local environments of the Si-H group, and on the medium. In order to estimate the validity of frequency evaluations we calculated the probabilities of HSiSi@sub 3-n@C@sub n@ structures as the functions of r assuming the homogeneous film and random bonding. We observed two slopes on the dependence of the Si-H stretching mode peak position on r. At r<0.16 only two structural configurations HSiSi@sub 3-n@C@sub n@ with n=0 & 1 dominate in a-SiC:H. For r>0.16 the inhomogeneity in medium is due to carbon clustering in the forms of mentioned above structures with n=2 & 3. The influence of structural configurations on optical properties was discussed.