engleski

The influence of substrate morphology on growth of thin silicon films by GISAXS

Thin Si films, with thicknesses between 100 and 300 nm, were deposited by PECVD (Plasma Enhanced Chemical Vapour Deposition) in silane gas (SiH4) highly diluted by hydrogen. The dilution was varied between 24 and 5% of silane in the working gas and power density between 5 and 15 mW/cm2. Two types of substrates were used. The first one was amorphous and relatively flat while second was polycrystalline with roughness of few tens of nano- meters. The crystal fraction in deposited samples, estimated by Raman spectroscopy, varied between 0 and 40% and individual crystal size was between 2 and 8 nm. The larger individual crystals are usually present in samples with highest crystal fraction. The sample density, estimated upon the spectral distribution of dielectric function in the infra red, was 15- 25% less than the crystalline silicon. GISAXS has been performed at the ELETTRA synchrotron radiation source, Trieste (Italy). The pattern of all the examined samples indicated the presence of not - spherical-like "particles" in the "bulk" of thin films, with average size between 1.5 and 4 nm. The "particles" are most probably voids and theirs shape indicate columnar growth. By GISAXS on the samples deposited on different substrates, the borderline deposition conditions between "transport limited growth" and growth dominantly influenced on plasma surface reactions was estimated.

amorphous silicon; nanocrystalline silicon; GISAXS; Raman

The Ninth International Conference on Surface X-Ray and Neutron Scattering - 9SXNS, The Ninth International Conference on Surface X-Ray and Neutron Scattering, Taipei, Taiwan