scholarly journals Facile and Controllable Synthesis of Large-Area Monolayer WS2 Flakes Based on WO3 Precursor Drop-Casted Substrates by Chemical Vapor Deposition

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 578 ◽  
Author(s):  
Biao Shi ◽  
Daming Zhou ◽  
Shaoxi Fang ◽  
Khouloud Djebbi ◽  
Shuanglong Feng ◽  
...  
Keyword(s):  
Energy Gap ◽  
Growth Parameters ◽  
Fluorescence Emission ◽  
Chemical Vapor ◽  
Optical Microscope ◽  
Edge Length ◽  
Controllable Synthesis ◽  
Large Area ◽  
Si Substrates ◽  
Potential Applications

Monolayer WS2 (Tungsten Disulfide) with a direct-energy gap and excellent photoluminescence quantum yield at room temperature shows potential applications in optoelectronics. However, controllable synthesis of large-area monolayer WS2 is still challenging because of the difficulty in controlling the interrelated growth parameters. Herein, we report a facile and controllable method for synthesis of large-area monolayer WS2 flakes by direct sulfurization of powdered WO3 (Tungsten Trioxide) drop-casted on SiO2/Si substrates in a one-end sealed quartz tube. The samples were thoroughly characterized by an optical microscope, atomic force microscope, transmission electron microscope, fluorescence microscope, photoluminescence spectrometer, and Raman spectrometer. The obtained results indicate that large triangular monolayer WS2 flakes with an edge length up to 250 to 370 μm and homogeneous crystallinity were readily synthesized within 5 min of growth. We demonstrate that the as-grown monolayer WS2 flakes show distinctly size-dependent fluorescence emission, which is mainly attributed to the heterogeneous release of intrinsic tensile strain after growth.

Growth and processing of heteroepitaxial 3C-SiC films for electronic devices applications

2012 ◽  
Vol 1433 ◽  
Author(s):  
A. Severino ◽  
M. Mauceri ◽  
R. Anzalone ◽  
A. Canino ◽  
N. Piluso ◽  
...  
Keyword(s):  
Growth Parameters ◽  
Low Cost ◽  
Electronic Devices ◽  
Young Modulus ◽  
Interesting Property ◽  
Large Area ◽  
Si Substrates ◽  
Application Fields ◽  
Sic Films

ABSTRACT3C-SiC is very attractive due the chance to be grown on large-area, low-cost Si substrates. Moreover, 3C-SiC has higher channel electron mobility with respect to 4H-SiC, interesting property in MOSFET applications. Other application fields where 3C-SiC can play a significant role are solar cells and MEMS-based sensors. In this work, we present a general overview of 3C-SiC growth on Si substrate. The influence of growth parameters, such as the growth rate, on the crystal quality of 3C-SiC films is discussed. The main issue for 3C-SiC development is the reduction of the stacking fault density, which shows an exponential decreasing trend with the film thickness tending to a saturation value of about 1000 cm-1. Some aspect of processing will be also faced with the realization of cantilever for Young modulus calculations and the implantation of Al ions for the study of damaging and recovery of the 3C-SiC crystal.

scholarly journals Evolution of large area TiS2-TiO2 heterostructures and S-doped TiO2 nano-sheets on titanium foils

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
S. Ahmad Etghani ◽  
E. Ansari ◽  
S. Mohajerzadeh
Keyword(s):  
Electron Microscopy ◽  
Vapor Deposition ◽  
Growth Parameters ◽  
Critical Role ◽  
Chemical Vapor ◽  
Rutile Phase ◽  
Xps Analysis ◽  
Large Area ◽  
Chlorine Gas ◽  
Titanium Foils

AbstractWe report a novel and facile method to synthesize sulfur-doped titanium oxide sheets and realize TiS2-TiO2 heterostructures by means of a sequential sulfurization and oxidation step in a dual-zone chemical vapor deposition furnace. The inclusion of chlorine and argon gases during the growth of such titanium-based compounds plays a critical role in the formation of desired geometries and crystalline structures. These heterostructures possess nano-whisker and nanosheet configurations, controlled by adjusting the growth parameters such as temperature, carrier gas and the sequencing between different steps of the growth. The evolution of these complex heterostructures has been investigated using Raman spectroscopy and EDS characterization. The presence of chlorine gas during the growth results in local TiS2 formation as well as faceted growth of TiO2 nanosheets through anatase to rutile phase change prohibition. The electron microscopy (TEM) images and diffraction pattern (SAED) characterization reveal the crystallinity and layered nature of grown structures, further demonstrating the 2D characteristics of S-doped nanosheets. The evolution of TiO2 on TiS2 heterostructures has also has been verified using XPS analysis. These highly featured nanostructures are suitable candidates to enhance the photocatalytic behavior of TiO2 nanostructures.

TEM and SEM Studies of MOCVD-Grown GaP on Si

1985 ◽  
Vol 62 ◽  
Author(s):  
M. M. Ai-Jassim ◽  
J. M. Olson ◽  
K. M. Jones
Keyword(s):  
Defect Density ◽  
Growth Parameters ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Structural Defects ◽  
Organic Chemical ◽  
Cross Sectional ◽  
Plan View ◽  
Si Substrates ◽  
Antiphase Domains

ABSTRACTGaP and GaP/GaAsP epitaxial layers have been grown on Si substrates by metal-organic chemical vapor deposition (MOCVD). These layers were characterized by SEM and TEM plan-view and cross-sectional examination. At growth temperatures ranging from 600° C to 800° C, the initial stages of growth were dominated by three-dimensional nucleation. TEM studies showed that at high temperatures the nuclei were generally misoriented with respect to each other yielding, upon coalescence, polycrystalline layers. The growth of single-crystal layers was achieved by nucleating a 30–50 nm layer of GaP at 500° C, followed by annealing and continued growth at 750 ° C. The defect density in these structures was investigated as a function of various growth parameters and substrate conditions. A high density of structural defects was generated at the Si/GaP interface. The use of 2° off (100) Si substrates resulted in GaP layers free of antiphase domains. These results and their implications are discussed.

Crack-free III-nitride structures (> 3.5 μm) on silicon

2011 ◽  
Vol 1324 ◽  
Author(s):  
Mihir Tungare ◽  
Jeffrey M. Leathersich ◽  
Neeraj Tripathi ◽  
Puneet Suvarna ◽  
Fatemeh (Shadi) Shahedipour-Sandvik ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
High Electron Mobility Transistor ◽  
Poor Quality ◽  
Organic Chemical ◽  
High Electron ◽  
Large Area ◽  
Si Substrates ◽  
Substrate Engineering ◽  
Gan On Si

ABSTRACTIII-nitride structures on Si are of great technological importance due to the availability of large area, epi ready Si substrates and the ability to heterointegrate with mature silicon micro and nanoelectronics. High voltage, high power density, and high frequency attributes of GaN make the III-N on Si platform the most promising technology for next-generation power devices. However, the large lattice and thermal mismatch between GaN and Si (111) introduces a large density of dislocations and cracks in the epilayer. Cracking occurs along three equivalent {1−100} planes which limits the useable device area. Hence, efforts to obtain crack-free GaN on Si have been put forth with the most commonly reported technique being the insertion of low temperature (LT) AlN interlayers. However, these layers tend to further degrade the quality of the devices due to the poor quality of films grown at a lower temperature using metal organic chemical vapor deposition (MOCVD). Our substrate engineering technique shows a considerable improvement in the quality of 2 μm thick GaN on Si (111), with a simultaneous decrease in dislocations and cracks. Dislocation reduction by an order of magnitude and crack separation of > 1 mm has been achieved. Here we combine our method with step-graded AlGaN layers and LT AlN interlayers to obtain crack-free structures greater than 3.5 μm on 2” Si (111) substrates. A comparison of these film stacks before and after substrate engineering is done using atomic force microscopy (AFM) and optical microscopy. High electron mobility transistor (HEMT) devices developed on a systematic set of samples are tested to understand the effects of our technique in combination with crack reduction techniques. Although there is degradation in the quality upon the insertion of LT AlN interlayers, this degradation is less prominent in the stack grown on the engineered substrates. Also, this methodology enables a crack-free surface with the capability of growing thicker layers.

Synthesis of uniformly distributed carbon nanotubes on a large area of Si substrates by thermal chemical vapor deposition

1999 ◽  
Vol 75 (12) ◽  
pp. 1721-1723 ◽  
Author(s):  
Cheol Jin Lee ◽  
Dae Woon Kim ◽  
Tae Jae Lee ◽  
Young Chul Choi ◽  
Young Soo Park ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Large Area ◽  
Thermal Chemical Vapor Deposition ◽  
Si Substrates

Large area depositon of Cd1-xZnxTe on GaAs and Si substrates by metalorganic chemical vapor deposition

1995 ◽  
Vol 24 (5) ◽  
pp. 483-489 ◽  
Author(s):  
N. H. Karam ◽  
R. Sudharsanan ◽  
A. Mastrovito ◽  
M. M. Sanfacon ◽  
F. T. J. Smith ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Chemical Vapor ◽  
Large Area ◽  
Si Substrates ◽  
Metalorganic Chemical

scholarly journals Large-area synthesis of monolayer MoSe2 films on SiO2/Si substrates by atmospheric pressure chemical vapor deposition

RSC Advances ◽  
2017 ◽  
Vol 7 (45) ◽  
pp. 27969-27973 ◽  
Author(s):  
Yu Zhao ◽  
Hyunjea Lee ◽  
Woong Choi ◽  
Weidong Fei ◽  
Cheol Jin Lee
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Atmospheric Pressure ◽  
Chemical Vapor ◽  
Large Area ◽  
Si Substrates ◽  
Pressure Chemical

We report the synthesis of large-area monolayer MoSe2 films extended up to a millimeter scale on SiO2/Si substrates by atmospheric pressure chemical vapor deposition (CVD).

TEM characterization of SiGeC material system

1994 ◽  
Vol 52 ◽  
pp. 840-841
Author(s):  
D. Chandrasekhar ◽  
David J. Smith ◽  
J. Kouvetakis ◽  
McD. Robinson
Keyword(s):  
Energy Gap ◽  
Compressive Strain ◽  
Compositional Analysis ◽  
Chemical Vapor ◽  
Standard Technique ◽  
Material System ◽  
Ion Milling ◽  
Bandgap Engineering ◽  
Si Substrates

The IV-IV material system, specifically Si1-xGex/Si, has generated considerable interest in the scientific community in recent years. The built-in compressive strain and composition of pseudomorphic Si1-xGex epilayers on Si substrates affect the band structure and energy gap, which are fundamental to bandgap engineering. This property has been used in demonstrating a heterojunction bipolar transistor with SiGe base, resulting in improved high-frequency performance over conventional transistors with Si bases. However, the thermal instability and lower critical thickness of Si1-xGex layers limits applications, in turn prompting investigation of the Si1-x-yGexCy system. Substitutional carbon incorporation in Si1-xGex is expected to relieve the strain in the epilayer and increase the energy gap, the latter being an important consideration in revolutionizing transistor technology. Recently, growth and characterization of pseudomorphic Si1-x-yGexCy and its photoluminescence properties have been reported.In our present study, we have characterized Si1-x-yGexCy samples grown on Si substrates by chemical vapor deposition. Different precursors and flow rates were used tovary the relative elemental compositions. Rutherford backscattering and secondary ion mass spectroscopy techniques were employed for compositional analysis and transmission electron microscopy was used to determine microstructure. Electron transparent specimens were prepared in cross-section by a standard technique, involving mechanical grinding, dimpling and argon ion-milling. TEM observations were made with JEOL 2000FX and JEOL 4000EX microscopes. Selected area diffraction patterns and optical diffractograms were used in determining the structure and lattice constants.

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