engleski

Estimation of amorphous silicon thin films density by optical methods

Due to leak of long range ordering, density of amorphous silicon is lower than in its crystalline form. By hydrogenation of material, the density difference becomes larger. In order to study the effect quantitatively, the series of thin amorphous hydrogenated silicon films with variation in hydrogen to silicon ratio from 6 to 31 at%, deposited by magnetron sputtering, was examined by UV-visible-IR spectroscopy and nuclear methods. The film density of deposited films was estimated by using tree different approaches. In the first one, the density was estimated by using EMA (Effective Medium Approximation) analysis of long wavelength dielectric function. In particularly, the basic and modified Maxwell-Garnett models were tested. The second set of values for density was obtained by analysis of stretching vibrations of Si-H bonds in IR part of spectrum, by using earlier published method. These results were compared with the results obtained by nuclear methods, allowing the discussion of compatibility and accuracy of all of applied methods.

amorphous silicon; FTIR; EMA; ERDA; voids

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