Percolation transport and filament formation in nanocrystalline silicon nanowires

2013 ◽  
Vol 113 (16) ◽  
pp. 164902 ◽  
Author(s):  
S. Fischer ◽  
C. Osorio ◽  
N. E. Williams ◽  
S. Ayas ◽  
H. Silva ◽  
...  
Keyword(s):  
Silicon Nanowires ◽  
Nanocrystalline Silicon ◽  
Filament Formation

Microcrystalline and Nanocrystalline Silicon: Simulation of Material Properties

2005 ◽  
Vol 862 ◽  
Author(s):  
R. Biswas ◽  
B. C. Pan ◽  
V. Selvaraj
Keyword(s):  
Silicon Nanowires ◽  
Amorphous Matrix ◽  
Volume Fraction ◽  
Crystalline Silicon ◽  
Amorphous Region ◽  
Nanocrystalline Silicon ◽  
Nano Crystalline ◽  
Crystalline Core ◽  
Silicon Structures ◽  
Dynamics Simulations

AbstractWe have simulated nano-crystalline silicon and microcrystalline silicon structures with varying crystallite volume fractions, using molecular dynamics simulations. The crystallite regions reside in an amorphous matrix. We find the amorphous matrix is better ordered in nanocrystalline-Si than in the homogenous amorphous silicon networks, consistent with the observed higher stability of H-diluted films. There is a critical size above which the crystallites are stable and may grow. Sub-nm size crystallites in the protocrystalline phase are found to reduce the strain of the amorphous matrix. We simulated micro-crystalline silicon with a substantial crystallite volume fraction. Microcrystalline structures exhibit a crystalline core surrounded by an amorphous shell with similarities to silicon nanowires. We find a relatively uniform H distribution in the amorphous region and a crystal-amorphous phase boundary that is not welldefined.

Thermoelectric Properties of p and n-type Nanocrystalline Silicon Nanowires with High Doping Levels

2012 ◽  
Vol 1408 ◽  
Author(s):  
F. Suriano ◽  
M. Ferri ◽  
S. Solmi ◽  
L. Belsito ◽  
A. Roncaglia ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Cross Section ◽  
Thermoelectric Properties ◽  
Silicon Nanowires ◽  
Low Cost ◽  
Nanocrystalline Silicon ◽  
Nanowire Diameter ◽  
Vertical Arrays ◽  
Heavily Doped ◽  
Average Size

ABSTRACTAn experimental investigation about the thermoelectric properties of heavily doped p ad n-type nanocrystalline silicon nanowires (NWs) is described. The NWs are produced with low cost CMOS compatible processes, highly customizable in terms of cross-section and placement, which enables the fabrication of both stacked NWs in nearly vertical arrays within nanostructured templates built with SiO2/Si3N4 thin films and individual, freestanding NWs suited for thermal conductivity measurements. The cross-section dimensions of the investigated NWs range between 30 and 120 nm in size and up to about 2 cm in length. The structure of the NWs, as shown by SEM/TEM observations, is nanocrystalline with average size of the nanocrystals in one dimension that is comparable with the nanowire diameter. On the NWs, Seebeck coefficient, electrical resistivity and thermal conductivity have been measured, yielding thermoelectric figure of merit (ZT) values of 0.2 at 300 K for the best case.

Optical Characterization of Oxide Encapsulated Silicon Nanowires of Various Morphologies

2008 ◽  
Vol 8 (8) ◽  
pp. 4202-4206 ◽  
Author(s):  
Sharon M. King ◽  
Shweta Chaure ◽  
Satheesh Krishnamurthy ◽  
Werner J. Blau ◽  
Alan Colli ◽  
...  
Keyword(s):  
Silicon Nanowires ◽  
Silicon Oxide ◽  
Crystalline Silicon ◽  
Silicon Nanowire ◽  
Visible Spectrum ◽  
Optical Characterization ◽  
Nanocrystalline Silicon ◽  
Oxide Nanowires ◽  
Emitting Species

The optical properties of four different silicon nanowire structures were investigated. Two of the samples consisted of spheres of nanocrystalline silicon en-capsulated by silicon oxide nanowires, with other two consisting of crystalline silicon nanowires coated by silicon oxide shells. The nanostructures produced by oxide assisted growth consisted of spheres of crystalline silicon encapsulated by silicon oxide shells. The absorption and photoluminescence of the different structures of the sample are investigated. The emitting species responsible for photoluminescence across the visible spectrum are discussed.

Numerical Modeling of Electrothermal Effects in Silicon Nanowires

2008 ◽  
Vol 1083 ◽  
Author(s):  
Cicek Boztug ◽  
Gokhan Bakan ◽  
Mustafa Akbulut ◽  
Ali Gokirmak ◽  
Helena Silva
Keyword(s):  
Temperature Profile ◽  
Silicon Nanowires ◽  
Electrical Current ◽  
Nanocrystalline Silicon ◽  
Heat Diffusion ◽  
Small Scale ◽  
Thomson Effect ◽  
Sem Images ◽  
Heat Diffusion Equation ◽  
Electrothermal Effects

AbstractAsymmetric melting was observed in electrically pulsed n-type (phosphorus) nanocrystalline silicon (nc-Si) wires fabricated lithographically. Scanning electron microscope (SEM) images taken from the pulsed wires showed that melting initiates from the ground terminal end of the wires instead of the center as initially expected. Asymmetry in the temperature profile is caused by heat exchanged between charge carriers and phonons when an electrical current is passed along a temperature gradient. This effect is known as Thomson effect, a thermoelectric heat transfer mechanism. One dimensional (1D) time dependent heat diffusion equation including Thomson heat term was solved to model the temperature profile on our structures. The modeling results show that Thomson effect introduces significant shifts in the temperature distribution. The effect of Thomson heat is modeled for various electrical pulse conditions and wires dimensions. Our results indicate that Thomson effect is significant in small scale electronic devices operating under high current densities.

Plasmon-assisted interaction of Si with light, for cancer hyperthermia and electromagnetic energy harvest

2020 ◽  
Vol 92 (2) ◽  
pp. 20101
Author(s):  
Behnam Kheyraddini Mousavi ◽  
Morteza Rezaei Talarposhti ◽  
Farshid Karbassian ◽  
Arash Kheyraddini Mousavi
Keyword(s):  
Silicon Nanowires ◽  
Metallic Nanoparticles ◽  
Near Infrared ◽  
Optical Transition ◽  
Electromagnetic Energy ◽  
Energy Harvest ◽  
Absorption Enhancement ◽  
Ir Absorption ◽  
Absorption Mechanism ◽  
Near Ir

Metal-assisted chemical etching (MACE) is applied for fabrication of silicon nanowires (SiNWs). We have shown the effect of amorphous sheath of SiNWs by treating the nanowires with SF6 and the resulting reduction of absorption bandwidth, i.e. making SiNWs semi-transparent in near-infrared (IR). For the first time, by treating the fabricated SiNWs with copper containing HF∕H2O2∕H2O solution, we have generated crystalline nanowires with broader light absorption spectrum, up to λ = 1 μm. Both the absorption and photo-luminescence (PL) of the SiNWs are observed from visible to IR wavelengths. It is found that the SiNWs have PL at visible and near Infrared wavelengths, which may infer presence of mechanisms such as forbidden gap transitions other can involvement of plasmonic resonances. Non-radiative recombination of excitons is one of the reasons behind absorption of SiNWs. Also, on the dielectric metal interface, the absorption mechanism can be due to plasmonic dissipation or plasmon-assisted generation of excitons in the indirect band-gap material. Comparison between nanowires with and without metallic nanoparticles has revealed the effect of nanoparticles on absorption enhancement. The broader near IR absorption, paves the way for applications like hyperthermia of cancer while the optical transition in near IR also facilitates harvesting electromagnetic energy at a broad spectrum from visible to IR.

Formation of Nanocrystalline Silicon in Tin-Doped Amorphous Silicon Films

2020 ◽  
Vol 65 (3) ◽  
pp. 236
Author(s):  
R. M. Rudenko ◽  
O. O. Voitsihovska ◽  
V. V. Voitovych ◽  
M. M. Kras’ko ◽  
A. G. Kolosyuk ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Crystalline Silicon ◽  
Solid Phase ◽  
Nanocrystalline Silicon ◽  
Recrystallization Temperature ◽  
Nanocrystalline Phase ◽  
Silicon Phase ◽  
Silicon Nanocrystallites ◽  
Lower Temperature ◽  
Two Stages

The process of crystalline silicon phase formation in tin-doped amorphous silicon (a-SiSn) films has been studied. The inclusions of metallic tin are shown to play a key role in the crystallization of researched a-SiSn specimens with Sn contents of 1–10 at% at temperatures of 300–500 ∘C. The crystallization process can conditionally be divided into two stages. At the first stage, the formation of metallic tin inclusions occurs in the bulk of as-precipitated films owing to the diffusion of tin atoms in the amorphous silicon matrix. At the second stage, the formation of the nanocrystalline phase of silicon occurs as a result of the motion of silicon atoms from the amorphous phase to the crystalline one through the formed metallic tin inclusions. The presence of the latter ensures the formation of silicon crystallites at a much lower temperature than the solid-phase recrystallization temperature (about 750 ∘C). A possibility for a relation to exist between the sizes of growing silicon nanocrystallites and metallic tin inclusions favoring the formation of nanocrystallites has been analyzed.

Giant Anisotropy of Conductivity in Hydrogenated Nanocrystalline Silicon Thin Films

1998 ◽  
Vol 536 ◽  
Author(s):  
A. B. Pevtsov ◽  
N. A. Feoktistov ◽  
V. G. Golubev
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Percolation Theory ◽  
Nanocrystalline Silicon ◽  
Spatial Light Modulators ◽  
Light Emitting ◽  
Light Modulators ◽  
Silicon Thin Films ◽  
Longitudinal Conductivity ◽  
Transverse Conductivity

AbstractThin (<1000 Å) hydrogenated nanocrystalline silicon films are widely used in solar cells, light emitting diodes, and spatial light modulators. In this work the conductivity of doped and undoped amorphous-nanocrystalline silicon thin films is studied as a function of film thickness: a giant anisotropy of conductivity is established. The longitudinal conductivity decreases dramatically (by a factor of 109 − 1010) as the layer thickness is reduced from 1500 Å to 200 Å, while the transverse conductivity remains close to that of a doped a- Si:H. The data obtained are interpreted in terms of the percolation theory.

Nanocrystalline silicon ( nc-Si ) from single ion beam sputtering

2003 ◽  
Vol 762 ◽  
Author(s):  
Z.B. Zhou ◽  
G.M. Hadi ◽  
R.Q. Cui ◽  
Z.M. Ding ◽  
G. Li
Keyword(s):  
Solar Cell ◽  
Ion Beam ◽  
Nanocrystalline Silicon ◽  
Silicon Films ◽  
Chamber Pressure ◽  
Ion Beam Sputtering ◽  
High Hydrogen ◽  
Beam Sputtering ◽  
Si Films ◽  
Nanocrystalline Silicon Films

AbstractBased on a small set of selected publications on the using of nanocrystalline silicon films (nc-Si) for solar cell from 1997 to 2001, this paper reviews the application of nc-Si films as intrinsic layers in p-i-n solar cells. The new structure of nc-Si films deposited at high chamber pressure and high hydrogen dilution have characters of nanocrystalline grains with dimension about several tens of nanometer embedded in matrix of amorphous tissue and a high volume fraction of crystallinity (60~80%). The new nc-Si material have optical gap of 1.89 eV. The efficiency of this single junction solar cell reaches 8.7%. This nc-Si layer can be used not only as an intrinsic layer and as a p-type layer. Also nanocrystalline layer may be used as a seed layer for the growth of polycrystalline Si films at a low temperature.We used single ion beam sputtering methods to synthesize nanocrystalline silicon films successfully. The films were characterized with the technique of X-ray diffraction, Atomic Force Micrographs. We found that the films had a character of nc-amorphous double phase structure. Conductivity test at different temperatures presented the transportation of electrons dominated by different mechanism within different temperature ranges. Photoconductivity gains of the material were obtained in our recent investigation.

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