Deposition of silicon nanostructures by thermal chemical vapour deposition (original) (raw)
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Low-pressure Chemical Vapour Deposition of Silicon Nanoparticles: Synthesis and Characterisation
2008
Semiconductor nanostructures such as quantum wells, quantum wires or quantum dots exhibit superior properties in comparison to their bulk forms. Quantum dots are described as zero-dimensional electron gas system, as carriers are confined in all the three directions. Density of states is discrete function of energy. Allowed energy spectrum is discrete like in an atom. Energy band gap is broadened due to carriers confinement. Semiconductor quantum dots exhibit typical coulomb blockade characteristic which is exploited for development of new generation of nanoelectronic devices namely single-electron transistor, memories, etc, whose operation depends on quantum mechanical tunneling of carriers through energy barriers. These semiconductor nanostructures emit light in visible range upon excitation by optical means. In recent years, research has been focused on different nano-scale materials; metals (Au, Ag, Fe, Mn, Ni), metal oxides (SnO 2 , ZnO 2 ), compound semiconductors (GaAs, GaAlAs, CdSe, CdS, GaN), and elemental semiconductors (silicon and germanium). As silicon is the most favoured material in the established integrated circuits manufacturing technology, research is being done for controlled synthesis and characterisation of Si nanoparticles. The Si nanoparticles have been synthesised on oxide and nitride layers over Si substrate by IC technology compatible low-pressure chemical vapour deposition technique. Atomic force microscopy (AFM) characterisation has been extensively carried out on the samples. It is shown that the tip radius and shape of tip lead to less accurate estimate of the actual size. The AFM images have been evaluated based on the real surface topography and shape of the tip. Photoluminescence (PL) studies have been performed to characterise the samples. The PL measurements showed visible light emission from synthesised silicon nanoparticles.
Characteristics Study of Silicon Nanoparticles Produced by Physical Vapour Deposition
American Journal of Materials Science, 2012
SiliconNanoparticles with thickness ranging between 40 to 50 nm and an average diameter of 80 nm were prepared by Physical Vapour Deposition (electron beam). The Nanoparticles showed blue and visible light emission from 300 A o to 900 A o , with peak intensity at 350-700 A o .Also AFM measurements were carried out and the regularity of silicon Nanoparticles was calculated and found to be equal to 0.3858 according to a quantitative hexagonal regularity calculation.
Low Pressure Chemical Vapor Deposition of Different Silicon Nanostructures
2006
The low pressure chemical vapor deposition technique was used to deposit different silicon nanostructures by varying the working gas composition and substrate temperature. Silan gas diluted with argon was used to deposit silicon nanocrystals on different temperatures between 650 and 900 o C. The p-doping films of polystalline Si films were prepared by using BCl 3 vapor. The SiO 2 nanostructures were deposited by using the mixture of SiH 4 +O 2 gasses and, in another case, of SiH 4 +N 2 O gasses. The structure and optical properties of such nanostructures were examined by Raman and IR spectroscopy, SEM analysis and electrical measurements.
ICNCRE 2013
The formation of silicon nanoclusters embedded in amorphous SiNx matrix is of great interest for optoelectronic devices such as solar cells and nanoelectronics such as thin films transistors ( TFTs). In this work, we investigate the properties of silicon nanocrystals formed in annealed low-pressure chemical vapor deposition in situ nitrogen doped silicon thin film (SiNx). Structural, optical and electrical characteristics of the thin film were studied by scanning electron microscopy (SEM), Raman spectroscopy, photoluminescence (PL) and fourpoint probe measurement. The results revealed a crystalline volume fraction of the annealed film exceeded 63 %, with a dominance of silicon nanocrystallites having the sizes within the range 2-4 nm and density ~1.09.10 12 /cm 2 . The electrical characterization has shown a good conductor behavior of silicon nanocrystals thin film. The PL spectrum, highlights that photoluminescence of film originates from quantum confinement effects.
2017
I studied the nanocrystalline silicon thin films by means of photoluminescent spectroscopy, Raman spectroscopy and Fourier-transformed infrared spectroscopy technique. The chemical bonding properties was studied by using the Fourier-transformed infrared spectroscopy in the range from500 cm -1 to 2300 cm -1 . Spectral peak at wave number of 1100 cm -1 is related to the Si-O-Si bonding configuration. Hydrogenation of film can be estimated by using spectral lines at 2100 cm -1 and 2080 cm -1 . The Si-O dipoles which are located into silicon film play great role because of electron affinity for oxygen. Photoluminescent (PL) properties are significant for the films which were made by using hydrogenation of silicon. Fourier-transformed infrared spectra of film’s absorption show the changes in chemicals in the film: from the oxygen incorporation into silicon to the elimination the Si-O bonding by adding the silicon tetra fluoride into electrochemical reactor, and increasing the Si-F densit...
2011
In this study, the fabrication of Si nanostructures by Au and SiH4 co-deposition technique using hot-wire chemical vapor deposition was demonstrated. A high deposition rate of 2.7 nm/s and a high density of silicon nanostructures with a diameter of about 140 nm were obtained at T-s of 250 degrees C. An increase in T-s led to a significant reduction in the size of the nanostructures. However, coalescence on the nanostructures was observed at T-s of 400 degrees C. The Si nanostructures exhibited a highly crystalline structure, which was induced by Au crystallites. The crystallite size and crystallinity of the Si nanostructures amplified with the increase in T. The presence of nanostructures enhanced the surface roughness of the samples and clearly reduced the reflection, especially in the visible region. (C) 2011 Elsevier B.V. All rights reserved.
Journal of Nanoscience and Nanotechnology, 2001
The outstanding demonstration of quantum confinement in Si nanocrystals (Si NC) in a SiC matrix requires the fabrication of Si NC with a narrow size distribution. It is understood without controversy that this fabrication is a difficult exercise and that a multilayer (ML) structure is suitable for such fabrication only in a narrow parameter range. This parameter range is sought by varying both the stoichiometric SiC barrier thickness and the Si-rich SiC well thickness between 3 nm and 9 nm and comparing them to single layers (SL). The samples processed for this investigation were deposited by plasma-enhanced chemical vapor deposition (PECVD) and subsequently subjected to thermal annealing at 1000-1100°C for crystal formation. Bulk information about the entire sample area and depth were obtained by structural and optical characterization methods: information about the mean Si NC size was determined from grazing incidence xray diffraction (GIXRD) measurements. Fourier-transform infrared spectroscopy (FTIR) was applied to gain insight into the structure of the Si-C network, and spectrophotometry measurements were performed to investigate the absorption coefficient and to estimate the bandgap E 04. All measurements showed that the influence of the ML structure on the Si NC size, on the Si-C network and on the absorption properties is subordinate to the influence of the overall Si content in the samples, which we identified as the key parameter for the structural and optical properties. We attribute this behavior to interdiffusion of the barrier and well layers. Because the produced Si NC are within the target size range of 2-4 nm for all layer thickness variations, we propose to use the Si content to adjust the Si NC size in future experiments.
Opto-structural studies of well-dispersed silicon nano-crystals grown by atom beam sputtering
Nanoscale Research Letters, 2012
Synthesis and characterization of nano-crystalline silicon grown by atom beam sputtering technique are reported. Rapid thermal annealing of the deposited films is carried out in Ar + 5% H 2 atmosphere for 5 min at different temperatures for precipitation of silicon nano-crystals. The samples are characterized for their optical and structural properties using various techniques. Structural studies are carried out by micro-Raman spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM), high resolution transmission electron microscopy, and selected area electron diffraction. The optical properties are studied by photoluminescence and UV-vis absorption spectroscopy, and bandgaps are evaluated. The bandgaps are found to decrease after rapid thermal treatment. The micro-Raman studies show the formation of nano-crystalline silicon in as-deposited as well as annealed films. The shifting and broadening in Raman peak suggest formation of nano-phase in the samples. Results of micro-Raman, photoluminescence, and TEM studies suggest the presence of a bimodal crystallite size distribution for the films annealed at higher temperatures. The results show that atom beam sputtering is a suitable technique to synthesize nearly mono-dispersed silicon nano-crystals. The size of the nano-crystals may be controlled by varying annealing parameters.
… Polonica-Series A …, 2012
In this work, we investigate the formation of silicon nanocrystals in annealed low pressure chemical vapor deposition in situ nitrogen doped silicon thin films (SiN x ) obtained at low temperature (465 • C) by using a mixture of disilane (Si 2 H 6 ) and ammonia (NH 3 ). Results show that nitrogen content in films plays an important role in defining the obtained films morphology in terms of crystallites sizes and their distribution. Indeed, according to the nitrogen content introduced in films, the crystalline state of films varies from a submicron crystalline structure to a nanocrystalline structure. An average silicon nanocrystalline size of 10 nm was obtained for film with x = 0.07 nitrogen content, annealed under a temperature of 850 • C during 2 h.
Materials Science in Semiconductor Processing, 2013
Silicon nanocrystals have been produced by thermal annealing of SiNx thin film obtained by low pressure chemical vapor deposition using a mixture between disilane and ammonia. Morphological, structural, and photoluminescence properties of the thin film were investigated using X-ray diffraction, scanning electron microscopy, Raman spectroscopy and photoluminescence spectroscopy. The results revealed a high crystallinity of film with a crystalline volume fraction exceeded 70 %, and a dominance of silicon nanocrystallites having the sizes within the range 2.5-5 nm and density ~1.98.10 12 /cm 2. The PL peaks consist of nanocrystalline silicon and amorphous silicon. The luminescence from the silicon nanocrystals was dominant.