Sensitivity of germanium content on growth conditions of silicon-germanium nanoparticles prepared in nonthermal capacitively-coupled plasmas

2020 ◽  
Vol 91 (2) ◽  
pp. 20801
Author(s):  
Md. Seraj Uddin ◽  
C. Vijayan ◽  
Jatindra Kumar Rath
Keyword(s):  
Silicon Germanium ◽  
Gas Flow ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Very High Frequency ◽  
Germanium Content ◽  
Capacitively Coupled ◽  
Hydrogen Flow ◽  
Alloy Nanocrystals ◽  
Coupled Plasmas

We report on the synthesis of Si1−x Ge x alloy nanocrystals by very-high-frequency plasma-enhanced chemical vapor deposition (VHF PECVD) technique at different silane to germane gas flow ratio (R) in a mixture of (H2+Ar) dilution gas and H2 dilution gas alone. TEM, SAED, EDS studies and HAADF-STEM mapping of the samples were done to investigate the NCs' size, crystallinity and distribution of Si and Ge in the Si1−x Ge x alloy NCs. The average estimated size of the NCs in all the samples are in the order of exciton Bohr radius of Ge (24.3 nm), thereby indicating the probability of good quantum confinement. The alloy nature of NCs was confirmed in Raman study. The content of Ge in SiGe NCs was evaluated from Raman spectra which show a direct correlation with the fraction of hydrogen flow in the dilution gas mixture.

Preparation and Characterization of SiC Nanoparticles for ATF-FCM

2018 ◽  
Vol 281 ◽  
pp. 22-27
Author(s):  
Zhao Chen ◽  
Rong Zheng Liu ◽  
Jia Xing Chang ◽  
Ma Lin Liu
Keyword(s):  
Gas Flow ◽  
Chemical Vapor ◽  
Pure Hydrogen ◽  
Fukushima Accident ◽  
Flow Rates ◽  
Sic Nanoparticles ◽  
Hydrogen Flow ◽  
Different Temperatures ◽  
Carrier Gas Flow

Accident Tolerant fuel (ATF) concept was put forward after the Fukushima accident. Among different kinds of ATF, Fully Ceramic Microencapsulated Fuels (FCM) have been paid more and more attention in recent years. SiC matrix is one of the important constituent parts in FCM fuel system, which is sintered from kinds of SiC powders. In this study, SiC nanoparticles were prepared by Fluidized Bed Chemical Vapor Deposition (FB-CVD) method using Hexamethyldisilane (HMDS) as precursor, aimed at reducing the sintering temperature and pressure of FCM-SiC matrix. Experiments of different temperatures with different argon gas ratios were carried out. It was found that good crystal SiC could be obtained from 850°C to 1250°C, under pure hydrogen or H2: Ar=15:1. Different H2 carrier gas flow rate tests were also conducted. With the increase of hydrogen flow rates, the SiC was transformed from 3C-SiC to other types, such as 6H or 15R, but no significant effect was found on particle shape. Based on the characterizations of XRD, SEM and TEM, the results showed the spherical SiC nanoparticles could be obtained as well as 20 nanometers in diameter at the condition of 1150°C, H2: Ar=15:1, under different hydrogen flow rates. Different hydrogen flow rates had little influence on the particle size of SiC nanoparticles.

Advanced Deposition Phase Diagrams for Guiding Si:H-Based Multijunction Solar Cells

2007 ◽  
Vol 989 ◽  
Author(s):  
Jason Collins ◽  
Nikolas J. Podraza ◽  
Jian Li ◽  
Xinmin Cao ◽  
Xunming Deng ◽  
...  
Keyword(s):  
Solar Cells ◽  
Phase Diagrams ◽  
Silicon Germanium ◽  
Chemical Vapor ◽  
Very High Frequency ◽  
Hydrogenated Silicon ◽  
Si Substrates ◽  
Cell Structures ◽  
Multijunction Solar Cells ◽  
Back Reflectors

AbstractPhase diagrams have been established to describe very high frequency (vhf) plasma-enhanced chemical vapor deposition (PECVD) processes for intrinsic hydrogenated silicon (Si:H) and silicon-germanium alloy (Si1-xGex:H) thin films using crystalline Si substrates that have been over-deposited with n-type amorphous Si:H (a-Si:H). The Si:H and Si1-xGex:H processes are applied for the top and middle i-layers of triple-junction a-Si:H-based n-i-p solar cells fabricated at University of Toledo. Identical n/i cell structures were co-deposited on textured Ag/ZnO back-reflectors in order to correlate the phase diagram and the performance of single-junction solar cells, the latter completed through over-deposition of the p-layer and top contact. This study has reaffirmed that the highest efficiencies for a-Si:H and a-Si1-xGex:H solar cells are obtained when the i-layers are prepared under maximal H2 dilution conditions.

Influence of inhomogeneous magnetic field on the characteristics of very high frequency capacitively coupled plasmas

2010 ◽  
Vol 107 (5) ◽  
pp. 053302 ◽  
Author(s):  
Kallol Bera ◽  
Shahid Rauf ◽  
Jason Kenney ◽  
Leonid Dorf ◽  
Ken Collins
Keyword(s):  
Magnetic Field ◽  
High Frequency ◽  
Inhomogeneous Magnetic Field ◽  
Very High Frequency ◽  
Capacitively Coupled ◽  
Coupled Plasmas ◽  
Very High

EFFECT OF ACETYLENE FLOW RATE ON ELECTROSORPTION CAPACITY OF CARBON NANOTUBE AND NANOFIBER COMPOSITE FILM ELECTRODES

2007 ◽  
Vol 14 (01) ◽  
pp. 135-139 ◽  
Author(s):  
X. Z. WANG ◽  
L. K. PAN ◽  
M. G. LI ◽  
Y. W. CHEN ◽  
R. M. CHENG ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Composite Film ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Nanofiber Composite ◽  
Spectra Analysis ◽  
Flow Rates ◽  
Hydrogen Flow ◽  
Successful Removal ◽  
Desalination Technology

Electrosorption of carbon nanotube and nanofiber (CNT–CNF) composite film electrodes was studied as a new desalination technology. The CNT–CNF composite film electrodes were grown on nickel sheets by low pressure thermal chemical vapor deposition. Different growth conditions at different acetylene flow rates of CNT–CNF composite film electrodes have been performed to obtain different crystallinities. The electrosorption experiments and Raman spectra analysis show the successful removal of ions with CNT–CNF composite film electrodes, depending on the optimal degree of crystalline perfection. In our work, optimal electrosorption was realized for the CNT–CNF composite film electrodes growing at 550°C with the acetylene and hydrogen flow rates of 30 and 200 sccm.

Novel Design of MOCVD Reactor with Three Radial Inward Flows for Epitaxial Growth of GaN Thin Films

2011 ◽  
Vol 308-310 ◽  
pp. 1037-1040
Author(s):  
Liao Qiao Yang ◽  
Jian Zheng Hu ◽  
Zun Miao Chen ◽  
Jian Hua Zhang ◽  
Alan G. Li
Keyword(s):  
Gas Flow ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Organic Chemical ◽  
Operating Pressure ◽  
Axisymmetric Mode ◽  
Mocvd Reactor ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition ◽  
D Model

In this paper, a novel super large metal organic chemical vapor deposition (MOCVD) reactor with three inlets located on the periphery of reactor was proposed and numerical evaluation of growth conditions for GaN thin film was characterized. In this design, the converging effects of gas flow in the radial direction could counterbalance the dissipation of metal organics source. CFD was used for the mathematical solution of the fluid flow, temperature and concentration fields. A 2-D model utilizing axisymmetric mode to simulate the gas flow in a MOCVD has been developed. The growth of GaN films using TMGa as a precursor, hydrogen as carrier gas was investigated. The effects of flow rates, mass fraction of various species, operating pressure, and gravity were analyzed and discussed, respectively. The numerical simulation results show all the fields distributions were in an acceptable range.

Observation of the standing wave effect in large-area, very-high-frequency capacitively coupled plasmas by using a fiber Bragg grating sensor

2018 ◽  
Vol 123 (22) ◽  
pp. 223304 ◽  
Author(s):  
Dao-Man Han ◽  
Yong-Xin Liu ◽  
Fei Gao ◽  
Xiang-Yu Wang ◽  
Ang Li ◽  
...  
Keyword(s):  
Fiber Bragg Grating ◽  
Standing Wave ◽  
High Frequency ◽  
Large Area ◽  
Very High Frequency ◽  
Wave Effect ◽  
Capacitively Coupled ◽  
Coupled Plasmas ◽  
Bragg Grating Sensor ◽  
Very High

Microstructure and Electric Transport Characteristic of Microcrystalline Silicon Films Fabricated by Very High Frequency Plasma Enhanced Chemical Vapor Deposition

2010 ◽  
Vol 663-665 ◽  
pp. 600-603
Author(s):  
Xiang Wang ◽  
Rui Huang ◽  
Jie Song ◽  
Yan Qing Guo ◽  
Chao Song ◽  
...  
Keyword(s):  
High Frequency ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Microcrystalline Silicon ◽  
Very High Frequency ◽  
Hydrogen Flow ◽  
Transmission Electron ◽  
High Frequency Plasma ◽  
Frequency Plasma ◽  
Very High

Microcrystalline silicon (μc-Si:H) film deposited on silicon oxide in a very high frequency plasma enhanced chemical vapor deposition with highly H2 dilution of SiH4 has been investigated by Raman spectroscopy and high resolution transmission electron microscopy. Raman spectroscopy results show that the crystalline volume fraction increases with increasing the hydrogen flow rate and for the hydrogen flow rate of 160 sccm, the crystalline volume fraction reaches to 67.5%. Nearly parallel columnar structures with complex microstructure are found from cross-sectional transmission electron microscopy images of the film. The temperature depend dark conductivity and activation energy are studied in order to investigate the electronic transport processes in the nc-Si films.

Hydrogenated Amorphous Silicon Germanium Alloys Grown by the Hot-Wire Chemical Vapor Deposition Technique

1998 ◽  
Vol 507 ◽  
Author(s):  
Brent P. Nelson ◽  
Yueqin Xu ◽  
D.L. Williamson ◽  
Bolko Von Roedern ◽  
Alice Mason ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Silicon Germanium ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapor ◽  
Hot Wire ◽  
Germanium Content ◽  
Amorphous Silicon Germanium ◽  
Hydrogenated Amorphous ◽  
Gas Ratio

ABSTRACTWe successfully grow high-quality hydrogenated amorphous-silicon-germanium alloys (a-SiGe:H) by the hot-wire chemical-vapor deposition (HWCVD) technique using silane and germane gas mixtures. These alloys display electronic properties as good as those grown by the plasma-enhanced chemical-vapor deposition (PECVD) technique, when comparing materials with the same optical bandgaps. However, we grow materials with good electrical properties at high deposition rates—up to 40 Å/s, compared to 1–4 Å/s for PECVD materials. Our alloys exhibit similar trends with increasing Ge content to alloys grown by PECVD. The defect density, the dark conductivity, and the degree of nanostructural heterogeneity (as measured by small-angle X-ray scattering) all increase with increasing germanium content in the alloy. The nanostructural heterogeneity displays a sharp transition between 9 at.% and 14 at.% germanium. PECVD- grown a-SiGe:H alloys exhibit a similar transition at 20 at.% Ge. The photoconductivity and the ambipolar diffusion length of the alloys decrease with increasing germanium content. For a fixed silane-to-germane gas ratio, all material properties improve substantially when increasing substrate temperature (Tsub) from 220°C to 375°C. Increasing Tsub also narrows the optical bandgap and lowers the hydrogen content in the alloys for the same germane-to-silane gas ratio.

Characterization of Silicon-Nitride Film Growth by Remote Plasmaenhanced Chemical-Vapor Deposition (Rpecvd)

1993 ◽  
Vol 334 ◽  
Author(s):  
Zhong Lu ◽  
Yi Ma ◽  
Scott Habermehl ◽  
Gerry Lucovsky
Keyword(s):  
Gas Flow ◽  
Film Growth ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Nitride Film ◽  
Silicon Nitride Film ◽  
Flow Rates ◽  
Plasma Generation ◽  
Atom Source ◽  
Rate Ratios

AbstractWe have characterized RPECVD formation of Si-nitride films by relating the chemical bonding in the deposited films to the growth conditions. Gas flow rates for different N- and Si-atom source gases have been correlated with (i) the film stoichiometry, i.e., the Si/N ratio, and the (ii) the growth rate. N2 and NH3 were used as N-atom source gases, and were either delivered (i) up-stream through the plasmageneration tube, or (ii) down-stream. Different flow-rate ratios of NH3/SiH4 were found for deposition of stoichiometric Si-nitride films using up-stream or down-stream introduction of NH3. This is explained in terms of competition between excitation and recombination processes for the N-atom precursor species. Stoichiometric nitride films could not be obtained using the N2 source gas for (i) either up-stream or down-stream delivery, and (ii) for plasma powers up to 50 W. This is attributed to the higher relative binding energy of N-atoms in N2 compared to NH3, and to significant N-atom recombination at high N2 flow rates through the plasma generation region.

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