| 1. |
- Barbe, Jeremy, et al.
(författare)
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Silicon nanocrystals on amorphous silicon carbide alloy thin films : Control of film properties and nanocrystals growth
- 2012
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Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 522, s. 136-144
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Tidskriftsartikel (refereegranskat)abstract
- The present study demonstrates the growth of silicon nanocrystals on amorphous silicon carbide alloy thin films. Amorphous silicon carbide films [a-Si1 − xCx:H (with x < 0.3)] were obtained by plasma enhanced chemical vapor deposition from a mixture of silane and methane diluted in hydrogen. The effect of varying the precursor gas-flow ratio on the film properties was investigated. In particular, a wide optical band gap (2.3 eV) was reached by using a high methane-to-silane flow ratio during the deposition of the a-Si1 − xCx:H layer. The effect of short-time annealing at 700 °C on the composition and properties of the layer was studied by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. It was observed that the silicon-to-carbon ratio in the layer remains unchanged after short-time annealing, but the reorganization of the film due to a large dehydrogenation leads to a higher density of SiC bonds. Moreover, the film remains amorphous after the performed short-time annealing. In a second part, it was shown that a high density (1 × 1012 cm− 2) of silicon nanocrystals can be grown by low pressure chemical vapor deposition on a-Si0.8C0.2 surfaces at 700 °C, from silane diluted in hydrogen. The influence of growth time and silane partial pressure on nanocrystals size and density was studied. It was also found that amorphous silicon carbide surfaces enhance silicon nanocrystal nucleation with respect to SiO2, due to the differences in surface chemical properties.
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| 2. |
- Perraud, Simon, et al.
(författare)
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Silicon nanocrystals : Novel synthesis routes for photovoltaic applications
- 2013
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Ingår i: Physica status solidi. A, Applied research. - : Wiley. - 0031-8965 .- 1521-396X. ; 210:4, s. 649-657
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Tidskriftsartikel (refereegranskat)abstract
- Novel processes were developed for fabricating silicon nanocrystals and nanocomposite materials which could be used as absorbers in third generation photovoltaic devices. A conventional high-temperature annealing technique was studied as a reference process, with some new insights in crystallisation mechanisms. Innovative methods for silicon nanocrystal synthesis at much lower temperature were demonstrated, namely chemical vapour deposition (CVD), physical vapour deposition (PVD) and aerosol-assisted CVD. Besides the advantage of low substrate temperature, these new techniques allow to fabricate silicon nanocrystals embedded in wide bandgap semiconductor host matrices, with a high density and a narrow size dispersion.
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| 3. |
- Quesnel, Etienne, et al.
(författare)
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Graphene-based technologies for energy applications, challenges and perspectives
- 2015
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Ingår i: Current Opinion in Chemical Engineering. - : IOP Publishing. - 2211-3398. ; 2:3, s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- Here we report on technology developments implemented into the Graphene Flagship European project for the integration of graphene and graphene-related materials (GRMs) into energy application devices. Many of the technologies investigated so far aim at producing composite materials associating graphene or GRMs with either metal or semiconducting nanocrystals or other carbon nanostructures (e.g., CNT, graphite). These composites can be used favourably as hydrogen storage materials or solar cell absorbers. They can also provide better performing electrodes for fuel cells, batteries, or supercapacitors. For photovoltaic (PV) electrodes, where thin layers and interface engineering are required, surface technologies are preferred. We are using conventional vacuum processes to integrate graphene as well as radically new approaches based on laser irradiation strategies. For each application, the potential of implemented technologies is then presented on the basis of selected experimental and modelling results. It is shown in particular how some of these technologies can maximize the benefit taken from GRM integration. The technical challenges still to be addressed are highlighted and perspectives derived from the running works emphasized.
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| 4. |
- Xie, Ling, 1982-, et al.
(författare)
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The visualization of Silicon nanoparticles by 3D electron tomography
- 2012
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Ingår i: European Microscopy Congress, Manchester, 2012.
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Konferensbidrag (refereegranskat)abstract
- Silicon nanoparticles (NP) size and spatial distribution in three-dimension (3D) are two critical parameters for the operation of “all-Si” tandem solar cells. The 3D distribution of Silicon NPs embedded in insulating or semiconducting matrices has attracted much interest for this third generation of photovoltaics. In this work, silicon NPs have been deposited by low pressure chemical vapour deposition (LPCVD) on a silicon carbide alloy thin-film at low temperature (700ºC) [1]. The aim of this study is to show how silicon nanoparticles are distributed in 3D on a silicon carbide thin film.
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