scholarly journals Spectroscopic Properties of Si-nc in SiOx Films Using HFCVD

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1415
Author(s):  
Zaira Jocelyn Hernández Simón ◽  
Jose Alberto Luna López ◽  
Alvaro David Hernández de la Luz ◽  
Sergio Alfonso Pérez García ◽  
Alfredo Benítez Lara ◽  
...  
Keyword(s):  
Band Gap ◽  
Thermal Annealing ◽  
Silicon Oxide ◽  
Chemical Vapor ◽  
Spectroscopic Properties ◽  
Spectroscopic Techniques ◽  
Vapor Deposition Technique ◽  
Potential Applications ◽  
Hot Filament ◽  
Short Time

In the present work, non-stoichiometric silicon oxide films (SiOx) deposited using a hot filament chemical vapor deposition technique at short time and simple parameters of depositions are reported. This is motivated by the numerous potential applications of SiOx films in areas such as optoelectronics. SiOx films were characterized with different spectroscopic techniques. The deposited films have interesting characteristics such as the presence of silicon nanoclusters without applying thermal annealing, in addition to a strong photoluminescence after applying thermal annealing in the vicinity of 1.5 eV, which may be attributed to the presence of small, oxidized silicon grains (less than 2 nm) or silicon nanocrystals (Si-nc). An interesting correlation was found between oxygen content, the presence of hydrogen, and the formation of defects in the material, with parameters such as the band gap and the Urbach energies. This correlation is interesting in the development of band gap engineering for this material for applications in photonic devices.

scholarly journals Study of the Thermal Annealing on Structural and Morphological Properties of High-Porosity A-WO3 Films Synthesized by HFCVD

Nanomaterials ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 1298 ◽  
Author(s):  
M. Cruz-Leal ◽  
O. Goiz ◽  
F. Chávez ◽  
G. F. Pérez-Sánchez ◽  
N. Hernández-Como ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Annealing ◽  
Chemical Vapor ◽  
Morphological Properties ◽  
High Porosity ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Vapor Deposition Technique ◽  
Hot Filament

High-porosity nanostructured amorphous tungsten OXIDE (a-WO3) films were synthesized by a Hot Filament Chemical Vapor Deposition technique (HFCVD) and then transformed into a crystalline WO3 by simple thermal annealing. The a-WO3 films were annealed at 100, 300, and 500 °C for 10 min in an air environment. The films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-Raman spectroscopy, high-resolution transmission electron microscopy (HR-TEM), and UV–vis spectroscopy. Results revealed that the a-WO3 films were highly porous, composed of cauliflower-like structures made of nanoparticles with average sizes of 12 nm. It was shown that the effect of annealing on the morphology of the a-WO3 films leads to a sintering process. However, the morphology is conserved. It was found that at annealing temperatures of 100 °C, the a-WO3 films are of an amorphous nature, while at 300 °C, the films crystallize in the monoclinic phase of WO3. The calculated bandgap for the a-WO3 was 3.09 eV, and 2.53 eV for the film annealed at 500 °C. Finally, the results show that porous WO3 films preserve the morphology and maintain the porosity, even after the annealing at 500 °C.

Si Nanocrystals Deposited by HFCVD

2012 ◽  
Vol 194 ◽  
pp. 204-208
Author(s):  
José Alberto Luna-López ◽  
G. Garcia-Salgado ◽  
J. Carrillo-López ◽  
Dianeli E. Vázquez-Valerdi ◽  
A. Ponce-Pedraza ◽  
...  
Keyword(s):  
Silicon Oxide ◽  
Chemical Vapor ◽  
Blue Shift ◽  
Wavelength Shift ◽  
Transmission Electron Microscopy Analysis ◽  
Quantum Confinement Effects ◽  
Transmission Electron ◽  
Vapor Deposition Technique ◽  
Electron Microscopy Analysis ◽  
Hot Filament

The structural and optical properties of Si nanocrystal (Si-nc) embedded in a matrix of off-stoichiometric silicon oxide (SiOx, x<2) films prepared by hot filament chemical vapor deposition technique were studied. The films emit a wide photoluminescent spectra and the maximum peak emission shows a blue-shift as the substrate temperature (Ts) decreases. Also, a wavelength-shift of the absorption edge in transmittance spectra is observed, indicating an increase in the energy band gap. The Si-nc’s size decreased from 6.5 to 2.5 nm as Ts was reduced from 1150 to 900 °C, as measured through High Resolution Transmission Electron Microscopy analysis. A combination of mechanisms is proposed to explain the photoluminescence in the SiOx films, which involve SiOx defects and quantum confinement effects.

Spray Chemical Vapor Deposition of CuInS2 Thin Films for Application in Solar Cell Devices

1997 ◽  
Vol 495 ◽  
Author(s):  
Jennifer A. Hollingsworth ◽  
William E. Buhro ◽  
Aloysius F. Hepp ◽  
Philip P. Jenkins ◽  
Mark A. Stan
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Band Gap ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Fused Silica ◽  
Direct Band Gap ◽  
Cuins2 Thin Films ◽  
Potential Applications ◽  
Direct Band

ABSTRACTChalcopyrite CuInS2 is a direct band gap semiconductor (1.5 eV) that has potential applications in photovoltaic thin film and photoelectrochemical devices. We have successfully employed spray chemical vapor deposition using the previously known, single-source, metalorganic precursor, (Ph3P)2CuIn(SEt)4, to deposit CuInS2 thin films. Stoichiometric, polycrystalline films were deposited onto fused silica over a range of temperatures (300–400 °C). Morphology was observed to vary with temperature: spheroidal features were obtained at lower temperatures and angular features at 400 °C. At even higher temperatures (500 °C), a Cu-deficient phase, CuIn5S8, was obtained as a single phase. The CuInS2 films were determined to have a direct band gap of ca. 1.4 eV.

Microbridge Nanoindentation Testing of Plasma-Enhanced Chemical Vapor Deposited Silicon Oxide Films

2004 ◽  
Vol 841 ◽  
Author(s):  
Zhiqiang Cao ◽  
Tong-Yi Zhang ◽  
Xin Zhang
Keyword(s):  
Residual Stresses ◽  
Thermal Annealing ◽  
Microelectromechanical Systems ◽  
Silicon Oxide ◽  
Chemical Vapor ◽  
Device Fabrication ◽  
Residual Deflection ◽  
Compressive Stresses ◽  
Stress Changes ◽  
Chemical Vapor Deposited

ABSTRACTPlasma-enhanced chemical vapor deposited (PECVD) silane-based oxides (SiOx) have been widely used in both microelectronics and MEMS (MicroElectroMechanical Systems) to form electrical and/or mechanical components. In this paper, a novel nanoindentation-based microbridge testing method is developed to measure both the residual stresses and Young's modulus of PECVD SiOx films. Our theoretical model employed a closed formula of deflection vs. load, considering both substrate deformation and the residual stresses in the thin films. In particular, the non-negligible residual deflection caused by excessive compressive stresses was taken into account. Freestanding microbridges made of PECVD SiOx films were fabricated using bulk micromachining techniques. To simulate the thermal processing in device fabrication, these microbridges were subjected to rapid thermal annealing (RTA) up to 800°C. A microstructure-based mechanism was applied to explain the experimental results of the residual stress changes in PECVD SiOx films after thermal annealing.

From helical nanowires, nanocrosses to aligned micro-carbon fibers

2003 ◽  
Vol 776 ◽  
Author(s):  
Hai-Feng Zhang ◽  
Chong-Min Wang ◽  
James S. Young ◽  
James E. Coleman ◽  
Lai-Sheng Wang
Keyword(s):  
Carbon Fibers ◽  
Chemical Vapor ◽  
Graphitic Carbon ◽  
Core Shell ◽  
Uniform Layer ◽  
C Fibers ◽  
Novel Structure ◽  
Vapor Deposition Technique ◽  
Potential Applications ◽  
Structural Characterizations

AbstractWe successfully synthesized helical core-shell crystalline SiC/SiO2 nanowires, core-shell crystalline SiC/C nano-crosses and well-aligned core-shell crystalline SiC/C fibers by using a chemical vapor deposition technique. For the helical crystalline SiC/SiO2 nanowires, the SiC core typically has diameters of 10-40 nm with a helical periodicity of 40-80 nm and is covered by a uniform layer of 30-60 nm thick amorphous SiO2. Detailed structural characterizations suggested that the growth of this novel structure was induced by screw dislocations on the nanometer scale. For the core-shell nanocrosses, the crystalline SiC core typically has diameters of 10 to 40 nm and is covered by a uniform layer of 80-110 nm graphitic carbon. The wellaligned SiC/C fibers were shown to be formed by two sequential steps: catalytic SiC growth and graphitic carbon nano-sheets coating. The helical nanowires and core-shell nanocrosses may have potential applications in nano-electronics. The formation mechanism of the carbon fibers suggested that fabrication of field emission filament carbon nano-fibers may be realized by using the aligned crystalline nanowires as templates.

Fabrication and Characterization of High Quality Micro Diamonds by Hot Filament CVD

2011 ◽  
Vol 325 ◽  
pp. 582-587
Author(s):  
T. Zhang ◽  
Fang Hong Sun ◽  
Bin Shen ◽  
Z.M. Zhang
Keyword(s):  
Silicon Wafer ◽  
Chemical Vapor ◽  
High Quality ◽  
Acetone Concentration ◽  
Vapor Deposition Technique ◽  
Hot Filament Cvd ◽  
Average Size ◽  
Hot Filament

The high quality micro diamonds with the euhedral diamond faces are fabricated by hot filament chemical vapor deposition technique (HFCVD). The high pressure and high temperature (HPHT) single crystal diamonds in size of 1 μm are used as seeds. In order to disperse the diamond seeds uniformly on a silicon wafer, the photoresist solution with diamond seeds are performed on the silicon wafer by a spin coater machine. The high substrate temperature and low acetone concentration are employed for decreasing the nucleation rate and accelerating the growth rate. The morphology and quality of the micro diamonds are observed and analyzed by SEM and Raman spectroscopy. After 4 hours of the deposition, the surface imperfections of the diamond seeds have disappeared completely, and the euhedral diamond faces with (111) and (100) begin to emerge. Subsequently, 8 hours of deposition leads to a final average size of approximately 4 μm. The micro diamonds have very high quality, and the surfaces appear flat and smooth in this stage. The results indicate that it is an effective way to eliminate the defects of the HPHT micro diamonds and develop high quality diamonds with well-defined morphology by HFCVD technique.

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