scholarly journals Photothermal Effects and Heat Conduction in Nanogranular Silicon Films

2021 ◽  
Author(s):  
Bayan A. Kurbanova ◽  
Gauhar K Mussabek ◽  
Viktor Y. Timoshenko ◽  
Vladimir Lysenko ◽  
Zhandos N. Utegulov
Keyword(s):  
Phonon Scattering ◽  
Hexagonal Phase ◽  
Fem Modeling ◽  
Element Mesh ◽  
Glass Substrates ◽  
Si Nanoparticles ◽  
Si Films ◽  
Conductive Properties ◽  
Difference Time

We present the results on photothermal (PT) and heat conductive properties of nanogranular silicon (Si) films synthesized by evaporation of colloidal droplets (drop-casting) of 100 ± 50 nm sized crystalline Si nanoparticles (NP) deposited on glass substrates. Finite difference time domain (FDTD) and finite element mesh (FEM) modeling of absorbed light intensity and photo-induced spatial temperature distribution across the Si NP films were well correlated with the local temperatures measured by micro-Raman spectroscopy and used for determination of heat conductivities in the films of various thicknesses. Cubic-to-hexagonal phase transition in these films caused by laser heating was found to be heavily influenced by the film thickness and heat conductive properties of glass substrate, on which the films were deposited. Heat conductivities across the drop-casted Si nanogranular films were found to be in the range of lowest heat conductivities of other types of nanostructurely voided Si films due to enhanced phonon scattering across inherently voided topology, weak NP-NP and NP-substrate interface bonding within nanogranular Si films.

scholarly journals Photothermal Effects and Heat Conduction in Nanogranular Silicon Films

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2379
Author(s):  
Bayan A. Kurbanova ◽  
Gauhar K. Mussabek ◽  
Viktor Y. Timoshenko ◽  
Vladimir Lysenko ◽  
Zhandos N. Utegulov
Keyword(s):  
Phonon Scattering ◽  
Hexagonal Phase ◽  
Interface Bonding ◽  
Fem Modeling ◽  
Element Mesh ◽  
Glass Substrates ◽  
Si Nanoparticles ◽  
Si Films ◽  
Conductive Properties ◽  
Difference Time

We present results on the photothermal (PT) and heat conductive properties of nanogranular silicon (Si) films synthesized by evaporation of colloidal droplets (drop-casting) of 100 ± 50 nm-sized crystalline Si nanoparticles (NP) deposited on glass substrates. Simulations of the absorbed light intensity and photo-induced temperature distribution across the Si NP films were carried out by using the Finite difference time domain (FDTD) and finite element mesh (FEM) modeling and the obtained data were compared with the local temperatures measured by micro-Raman spectroscopy and then was used for determining the heat conductivities k in the films of various thicknesses. The cubic-to-hexagonal phase transition in Si NP films caused by laser-induced heating was found to be heavily influenced by the film thickness and heat-conductive properties of glass substrate, on which the films were deposited. The k values in drop-casted Si nanogranular films were found to be in the range of lowest k of other types of nanostructurely voided Si films due to enhanced phonon scattering across inherently voided topology, weak NP-NP and NP-substrate interface bonding within nanogranular Si films.

Rapid Epitaxial Growth of Si and SiGe Mono-Crystalline Films on Silicon-on-Glass Substrates by Reactive CVD Using SiH4, GeH4, and F2

2012 ◽  
Vol 1426 ◽  
pp. 331-337
Author(s):  
Hiroshi Noge ◽  
Akira Okada ◽  
Ta-Ko Chuang ◽  
J. Greg Couillard ◽  
Michio Kondo
Keyword(s):  
Epitaxial Growth ◽  
Heating Temperature ◽  
Exothermic Reaction ◽  
Epitaxial Films ◽  
Si Substrates ◽  
Glass Substrates ◽  
Good Crystallinity ◽  
Crystalline Films ◽  
Si Films ◽  
First Time

ABSTRACTWe have succeeded in the rapid epitaxial growth of Si, Ge, and SiGe films on Si substrates below 670 ºC by reactive CVD utilizing the spontaneous exothermic reaction between SiH4, GeH4, and F2. Mono-crystalline SiGe epitaxial films with Ge composition ranging from 0.1 to 1.0 have been successfully grown by reactive CVD for the first time.This technique has also been successfully applied to the growth of these films on silicon-on-glass substrates by a 20 - 50 ºC increase of the heating temperature. Over 10 μm thick epitaxial films at 3 nm/s growth rate are obtained. The etch pit density of the 5.2 μm-thick Si0.5Ge0.5 film is as low as 5 x 106 cm-2 on top. Mobilities of the undoped SiGe and Si films are 180 to 550 cm2/Vs, confirming the good crystallinity of the epitaxial films.

scholarly journals Responses of dipole-source reflected shear waves in acoustically slow formations

2019 ◽  
Author(s):  
Hao Wang ◽  
Ning Li ◽  
Caizhi Wang ◽  
Hongliang Wu ◽  
Peng Liu ◽  
...  
Keyword(s):  
Finite Difference Time Domain ◽  
Dipole Source ◽  
Sh Wave ◽  
S Wave ◽  
High Fracture ◽  
S Waves ◽  
Angle Fracture ◽  
Dip Angle ◽  
Difference Time

Abstract In the process of dipole-source acoustic far-detection logging, the azimuth of the fracture outside the borehole can be determined with the assumption that the SH–SH wave is stronger than the SV–SV wave. However, in slow formations, the considerable borehole modulation highly complicates the dipole-source radiation of SH and SV waves. A 3D finite-difference time-domain method is used to investigate the responses of the dipole-source reflected shear wave (S–S) in slow formations and explain the relationships between the azimuth characteristics of the S–S wave and the source–receiver offset and the dip angle of the fracture outside the borehole. Results indicate that the SH–SH and SV–SV waves cannot be effectively distinguished by amplitude at some offset ranges under low- and high-fracture dip angle conditions, and the offset ranges are related to formation properties and fracture dip angle. In these cases, the fracture azimuth determined by the amplitude of the S–S wave not only has a $180^\circ $ uncertainty but may also have a $90^\circ $ difference from the actual value. Under these situations, the P–P, S–P and S–S waves can be combined to solve the problem of the $90^\circ $ difference in the azimuth determination of fractures outside the borehole, especially for a low-dip-angle fracture.

Optical, Structural and Electrical Characteristics of Explosively Crystallized Si Thin Films on Glass Substrates

1981 ◽  
Vol 4 ◽  
Author(s):  
G. Auvert ◽  
D. Bensahel ◽  
A. Perio ◽  
F. Morin ◽  
G.A. Rozgonyi ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Properties ◽  
Laser Annealing ◽  
The State ◽  
Electrical Characteristics ◽  
Glass Substrates ◽  
Explosive Crystallization ◽  
Cw Laser ◽  
Structural And Electrical Properties ◽  
Si Films

ABSTRACTExplosive Crystallization occurs in cw laser annealing on a-Si films deposited on glass substrates at laser scan speeds higher than 30 cm/sec. Optical, structural and electrical properties of the crystallized films at various laser scan speeds confirm the existence of two kinds of explosive growth depending on the state of crystallinity of the starting material.

Developing of the optimal shape and reinforcement structure of the specimen for adequate determination of the tensile strength in unidirectional composites

2021 ◽  
Vol 87 (2) ◽  
pp. 43-55
Author(s):  
A. N. Polilov ◽  
D. D. Vlasov ◽  
N. A. Tatus’
Keyword(s):  
Stress Concentration ◽  
Specimen Thickness ◽  
Fem Modeling ◽  
Cross Sectional ◽  
Reinforcement Structure ◽  
Unidirectional Composites ◽  
Manufacturing Testing ◽  
Rectangular Strips ◽  
Specimen Shape

Unidirectional composites exhibit the highest strength when stretched along the fibers. However, the proper determination of the strength faces great methodological difficulties. The main problems of tensile testing of polymer composites consisted in developing of the specimen shape and the method of specimen fixation which ensure the minimum impact of the stress concentration near the grips on the strength measurements. A conventional shape of the specimen with fillets is unsuitable for unidirectional polymers due to the splitting occurred in the fillet zones upon loading. Therefore, the specimens are usually standardized in the form of rectangular strips fixed using pads or special grips which provide constant transverse forces. However, with such a specimen shape, a significant stress concentration inevitably occurs at the edge of grips and the lower the ratio of the interlayer shear modulus to the longitudinal Young’s modulus, the greater the stress concentration impact. For the purpose of the most correct determination of the strength we propose to use specimens with smoothly varying dimensions at the same cross-sectional area which ensures keeping the total number of unbroken fibers in each section. The specimen thickness decreases when moving from the working part of the specimen to the gripping part, whereas the width (while maintaining the section area) grows to prevent the specimen collapsing resulting from transverse forces in standard self-tightening grips. Analytical and FEM modeling is performed to select a rational contour shape. Technological equipment has been developed and a procedure of manufacturing testing specimens has been worked out. The tensile test of specially manufactured curvilinear reinforced specimens showed higher strength values compared to standard rectangular strips or specimens with semicircular fillets.

Stress Reduction of Amorphous Silicon Deposited by PECVD

2016 ◽  
Vol 1812 ◽  
pp. 109-116
Author(s):  
César B. Pérez ◽  
C. Reyes-Betanzo
Keyword(s):  
Residual Stress ◽  
Amorphous Silicon ◽  
Thermal Annealing ◽  
Stress Reduction ◽  
Microfluidic Devices ◽  
Wet Etching ◽  
Glass Substrates ◽  
Deposition Power ◽  
Si Films ◽  
Deposition Conditions

ABSTRACTAmorphous silicon (α-Si) was deposited on glass substrates by PECVD at different deposition conditions in order to characterize the residual stress on the film. Subsequently, a thermal-annealing was applied for different times at 400 °C in a N2 atmosphere, aiming to reduce the stress in the films. The deposition power was between 15 and 30 W at 13.56 MHz, the pressure in the chamber was adjusted in a range from 600 to 900 mTorr, and the temperature was varied from 140 to 200 °C. The stress was determined by using the Stoney equation, measuring the curvature and thickness of the α-Si films with a stylus profilometer. A deposition rate between 7-24 nm/min was obtained, and the time for thermal-annealing needed to reduce the stress was reduced from 10 to 2-4 h, obtaining a minimum compressive stress of 17 MPa. With this value of stress, it was possible to use the α-Si as masking material for wet etching of glass during the manufacturing of microfluidic devices, in order to obtain microstructures in the glass with 150 μm in depth.

scholarly journals Size Determination of Polystyrene Sub-Microspheres Using Transmission Spectroscopy

2020 ◽  
Vol 10 (15) ◽  
pp. 5232
Author(s):  
Tien Van Nguyen ◽  
Linh The Pham ◽  
Khuyen Xuan Bui ◽  
Lien Ha Thi Nghiem ◽  
Nghia Trong Nguyen ◽  
...  
Keyword(s):  
Time Domain ◽  
Finite Difference Time Domain ◽  
Fdtd Simulation ◽  
Transmission Spectra ◽  
Experimental Transmission ◽  
Straightforward Method ◽  
Quartz Substrates ◽  
Difference Time ◽  
Good Agreement

Nano/micro polystyrene (PS) beads have found many applications in different fields spanning from drug delivery, bio-diagnostics, and hybrid plasmonics to advanced photonics. The sizes of the PS beads are an important parameter, especially in plasmonic and photonic experiments. In this work, we demonstrate a quick and straightforward method to estimate the diameters of sub-microspheres (0.2 μm to 0.8 μm) using the transmission spectra of a close-packed monolayer of polystyrene beads on glass or quartz substrates. Experimental transmission spectra of the PS monolayers were verified against finite-difference time-domain (FDTD) simulation and showed good agreement. The effects of the substrates on the transmission spectra and, hence, the accuracy of the method were also studied by simulation, which showed that common transparent substrates only cause minor deviation of the PS bead sizes calculated by the proposed method.

scholarly journals Characterization of Defects and Stress in Polycrystalline Silicon Thin Films on Glass Substrates by Raman Microscopy

2011 ◽  
Vol 2011 ◽  
pp. 1-14 ◽  
Author(s):  
Kuninori Kitahara ◽  
Toshitomo Ishii ◽  
Junki Suzuki ◽  
Takuro Bessyo ◽  
Naoki Watanabe
Keyword(s):  
Grain Boundaries ◽  
Polycrystalline Silicon ◽  
Solid Phase ◽  
Raman Microscopy ◽  
Laser Crystallization ◽  
Local Vibration ◽  
Optical Phonon Mode ◽  
Glass Substrates ◽  
Silicon Thin Films ◽  
Si Films

Raman microscopy was applied to characterize polycrystalline silicon (poly-Si) on glass substrates for application as thin-film transistors (TFTs) integrated on electronic display panels. This study examines the crystallographic defects and stress in poly-Si films grown by industrial techniques: solid phase crystallization and excimer laser crystallization (ELC). To distinguish the effects of defects and stress on the optical-phonon mode of the Si–Si bond, a semiempirical analysis was performed. The analysis was compared with defect images obtained through electron microscopy and atomic force microscopy. It was found that the Raman intensity for the ELC film is remarkably enhanced by the hillocks and ridges located around grain boundaries, which indicates that Raman spectra mainly reflect the situation around grain boundaries. A combination of the hydrogenation of films and the observation of the Si-hydrogen local-vibration mode is useful to support the analysis on the defects. Raman microscopy is also effective for detecting the plasma-induced damage suffered during device processing and characterizing the performance of Si layer in TFTs.

Spectroscopic Ellipsometry of the Optical Functions of Some Widely Used Organic Light Emitting Diodes (OLEDs) Materials.

2005 ◽  
Vol 871 ◽  
Author(s):  
Z. T. Liu ◽  
C. C. Oey ◽  
A. B. Djuriši ◽  
C. Y. Kwong ◽  
C. H. Cheung ◽  
...  
Keyword(s):  
Spectroscopic Ellipsometry ◽  
Indium Tin Oxide ◽  
High Vacuum ◽  
Light Emitting ◽  
Glass Substrates ◽  
Optical Functions ◽  
Conducting Materials ◽  
Ito Glass ◽  
Polystyrene Sulfonic Acid

AbstractIn this work, optical functions of some widely used OLEDs materials 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), tris (8-hydroxyquinoline) aluminum (Alq3), (N,N′-di(naphthalene-1-yl)-N,N′- diphenylbenzidine (NPB),poly(3,4,-ethylene dioxythiophene):polystyrene sulfonic acid (PEDOT:PSS) and indium tin oxide (ITO)) were studied using spectroscopic ellipsometry (SE) in the spectral range from 1.55 eV to 4.1 eV (wavelength range of 300 nm to 800 nm). The samples were prepared either by thermal evaporation in high vacuum or spin-coating of thin films onto glass substrates. For determination of the optical functions of ITO, commercial ITO glass was used. Measurements at different incident angles were performed to determine whether the samples can be considered isotropic. The SE data were modeled using an oscillator model (Lorentz for semiconducting and Lorentz-Drude for conducting materials). The absorption spectra were also measured, and the comparison with the data determined by SE is given.

Sign in / Sign up

Export Citation Format

Share Document