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Study of amorphous nanocrystalline thin silicon films by grazing‐incidence small‐angle X‐ray scattering
Author(s) -
Gracin Davor,
Bernstorff Sigrid,
Dubcek Pavo,
Gajovic Andreja,
Juraic Krunoslav
Publication year - 2007
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889807002075
Subject(s) - materials science , analytical chemistry (journal) , thin film , amorphous solid , silane , grazing incidence small angle scattering , scattering , volume fraction , chemical vapor deposition , crystal (programming language) , optics , crystallography , chemistry , small angle neutron scattering , composite material , nanotechnology , neutron scattering , programming language , physics , chromatography , computer science
Thin Si films, with thicknesses between 100 and 400 nm, were deposited by radio frequency plasma enhanced chemical vapour deposition in silane gas (SiH 4 ) highly diluted by hydrogen. The growing conditions were varied to obtain different degrees of crystal fractions and a variety in individual crystal sizes. The crystalline to amorphous volume fraction, as estimated by Raman spectroscopy, varied from 5 to 45% while the individual crystal sizes varied from 2 to 8 nm. The average density of the samples was estimated by using near infrared spectroscopy and the effective medium approximation. All samples were porous and contained void volume fraction between 15 and 25%. Grazing‐incidence small‐angle X‐ray scattering has been performed at the ELETTRA synchrotron radiation source (Trieste, Italy). The scattering patterns of all examined samples indicate the presence of `particles' in the `bulk' of the thin films with gyration radii in the range of 2 to 5 nm. The higher values were found for the samples with a higher crystalline fraction. The size and the size distribution of `particles' depend upon the deposition conditions. The samples which had been deposited with a higher discharge power and a lower silane fraction had larger particles and the roughness of their surface was higher.