Abstract
Structural, compositional, morphological, and optical properties of silicon nanocrystal (Si-nc) embedded in a matrix of non-stoichiometric silicon oxide (SiOx) films were studied. SiOx films were prepared by hot filament chemical vapor deposition technique in the 900 to 1,400°C range. Different microscopic and spectroscopic characterization techniques were used. The film composition changes with the growth temperature as Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy reveal. High-resolution transmission electron microscopy supports the existence of Si-ncs with a diameter from 1 to 6.5 nm in the matrix of SiOx films. The films emit in a wide photoluminescent spectrum, and the maximum peak emission shows a blueshift as the growth temperature decreases. On the other hand, transmittance spectra showed a wavelength shift of the absorption border, indicating an increase in the energy optical bandgap, when the growth temperature decreases. A relationship between composition, Si-nc size, energy bandgap, PL, and surface morphology was obtained. According to these results, we have analyzed the dependence of PL on the composition, structure, and morphology of the Si-ncs embedded in a matrix of non-stoichiometric SiOx films.
Highlights
Since the discovery of light emission from porous silicon [1], an intense investigation of materials compatible with silicon technology with excellent optical properties has been under development
silicon oxide (SiOx) films deposited by hot filament chemical vapor deposition (HFCVD) at different growth temperatures were analyzed
The strongest PL was obtained for SiOx films deposited at 1,150°C
Summary
Since the discovery of light emission from porous silicon [1], an intense investigation of materials compatible with silicon technology with excellent optical properties has been under development. Materials containing silicon nanocrystal (Si-nc) have attracted the interest of researchers due to their optical properties. A great variety of materials with these characteristics have been studied [2,3,4,5]. One of these materials is the nonstoichiometric silicon oxide (SiOx); this material contains Si excess agglomerates to create Si nanoparticles embedded in an oxide matrix. SiOx shows some special compositional, structural, morphological, and optical properties that vary with the Si excess. The optical characteristics of SiOx films can be varied with the growth temperatures. Refractive index varies from 1.6 to 2.4 when the growth temperature is changed; SiOx
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