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|Type:||Artigo de periódico|
|Title:||Infrared studies on films of carbosilazane and siloxazane networks|
de Moraes, MAB
|Abstract:||The present work describes the effects of diluting hexamethyldisilazane (HMDSN) vapor either in pure argon or in oxygen-argon mixtures on the solid film deposited from the resulting plasma. Such a dilution provides a manner of incorporating controllable amounts of Si-O groups into the solid film. The characterization of the films investigated here was made by longitudinal and transverse optical (LO and TO, respectively) functions in the mid-infrared calculated through the Kramers-Kronig analysis of transmittance spectra. The infrared analysis showed that the films were formed by silicon-centered distorted tetrahedra of the following type: Si(CH3)(x)BU(2-0.5x), where 0 <= x <= 3 and BU stands for bridging unit. For the sample deposited in the absence of O-2 in the discharge, BU = CH2 and NH; for the samples deposited with an O-2 flow rate (f(O2)) of 2.5 and 10 sccm, BU = CH2, NH, and O; and for the sample deposited with f(O2) of 20 sccm, BU = NH and O. The Delta(LO-TO) for the Si-O asymmetrical stretching increased from 0 (f(O2) = 0 sccm) to 73 cm(-1) (f(O2) = 20 sccm), while for the Si-N asymmetrical stretching it decreased from 20 (f(O2) = 0 sccm) to 3 cm(-1) (f(O2) = 20 sccm). These observations signal an increase in the Si-O-Si network and a decrease in the Si-NH-Si network as the oxygen flow increased. An interesting conclusion drawn from our analysis of the Si-H stretching mode position and Delta(LO-TO) for the AS1 band is that the films deposited in the presence of O-2 are not structurally homogeneous, but have domains with different proportions of O bridges.|
|Editor:||Amer Chemical Soc|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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