Estudo das propriedades termomecanicas e estruturais de filmes finos amorfos de carbono e nitretos de carbono / Study of the thermomechanical and structural properties in amorphous carbon and carbon nitride

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

In this work, we studied thenno mechanical and structural properties of hydrogenated amorphous carbon (a-C: H), hydrogenated carbon nitride (a-C:H:Nx) and carbon nitride (a-C:Nx) thin films. Two techniques were used to prepare the samples: glow discharge for depositing hydrogenated amorphous carbon (a-C:H) and carbon nitride (a-C:H:Nx) and ion beam assisting deposition (IBAD) for unhydrogenated amorphous carbon nitride (a-C:Nx) films. The curvature of the film/substrate composites was measured using the thermally induced bending (TIB) technique in order to determine the stress of the films. By varying the temperature and using films deposited in several different substrates one was able to obtain the coefficient of thermal expansion (CTE) and the biaxial modulus (E/(l-v)) of the films. Complementarily to this technique, we perfonned nanohardness measurements, which also allows to obtaining the elastic constant (E/(1-v2)) as well. Using both techniques, TIB and nanohardness, we determined, for the first time, separately the Young s modulus (E) and the Poisson s ratio (v) of a-C:H, a-C:H:Nx and a-C:Nx. These thermomechanical properties were investigated as a function of sp2-bond, or graphite s cluster, concentrations, using the following techniques: EELS, infrared spectroscopy, visible and ultraviolet Raman spectroscopy. The influence of the incorporation of nitrogen in the hydrogenated and unhydrogenated matrixes is discussed. We observed that the CTE of a-C:H depends strongly on the concentration of Sp2 sites approaching the value for graphite as the concentration tends to 100 %. The nitrogen incorporation increases the cluster formation in matrixes, inducing a substantial increase of the CTE of the fi1ms. On the other hand, in the matrix free of hydrogen it was observed that the CTE is not strongly influenced by the nitrogen concentration. These observations indicate that hydrogen plays an important role on the value of the CTE in amorphous carbon nitrogen films

ASSUNTO(S)

amorphous semiconductors raman graphite carbono - propriedades termomecanicas espectroscopia de thermomechanical properties semicondutores amorfos grafite nitrogen nitrogenio raman spectroscopy carbon

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