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Molecular hydrogen‐induced nucleation of hydrogenated silicon nanocrystals at low temperature
Author(s) -
Filali Larbi,
Brahmi Yamina,
Sib Jamal Dine,
Kail Fatiha,
Bouizem Yahya,
Benlakehal Djamel,
Zellama Kacem,
Bouhekka Ahmed,
Kebab Aissa,
Chahed Larbi
Publication year - 2019
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.6614
Subject(s) - materials science , raman spectroscopy , nanocrystalline silicon , silicon , amorphous solid , ellipsometry , nucleation , amorphous silicon , annealing (glass) , porous silicon , chemical engineering , surface roughness , analytical chemistry (journal) , thin film , nanotechnology , composite material , crystallography , crystalline silicon , chemistry , optics , optoelectronics , organic chemistry , engineering , physics
Highly crystallized hydrogenated silicon layers were obtained via the treatment of hydrogenated polymorphous silicon films in a molecular hydrogen ambient. This contrasts other postdeposition studies that obtained nanocrystalline silicon films but necessitated either a plasma activation or high‐temperature annealing. The structure of the samples was analyzed by Raman spectroscopy to determine the crystallite volume fraction, which was found to increase up to 80% within 1 hour of treatment. Atomic force microscopy (AFM) showed that the roughness of the surfaces was found to increase after the H 2 treatment. Optical transmission and spectroscopic ellipsometry revealed the pronounced porosity of the films characterized by a static refractive index that is below three, which is a low value for hydrogenated silicon films and a void fraction that is around 15% in the bulk of the films. The effect of the hydrogen molecules on the structure of the films was discussed in terms of the compressive stress exerted by the molecules, trapped in structural inhomogeneities, on the amorphous tissue. It is suggested that for this process to take effect, the films need to be porous and that the amorphous network needs to be in a “relaxed” state.