scholarly journals Synthesis and Characterization of Highly Crystalline Vertically Aligned WSe2 Nanosheets

2020 ◽  
Vol 10 (3) ◽  
pp. 874 ◽  
Author(s):  
Ayrton Sierra-Castillo ◽  
Emile Haye ◽  
Selene Acosta ◽  
Carla Bittencourt ◽  
J.-F. Colomer
Keyword(s):  
Photoelectron Spectroscopy ◽  
Gas Sensing ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Microscopies ◽  
Vapor Deposition Technique ◽  
Pressure Chemical ◽  
Vertically Aligned

Here, we report on the synthesis of tungsten diselenide (WSe2) nanosheets using an atmospheric pressure chemical vapor deposition technique via the rapid selenization of thin tungsten films. The morphology and the structure, as well as the optical properties, of the so-produced material have been studied using electron microscopies, X-ray photoelectron spectroscopy, photoluminescence, UV–visible and Raman spectroscopies, and X-ray diffraction. These studies confirmed the high crystallinity, quality, purity, and orientation of the WSe2 nanosheets, in addition to the unexpected presence of mixed phases, instead of only the most thermodynamically stable 2H phase. The synthesized material might be useful for applications such as gas sensing or for hydrogen evolution reaction catalysis.

Deposition and Properties of AlN Films Prepared by Low Pressure CVD with a Metalorganic Precursor

1993 ◽  
Vol 335 ◽  
Author(s):  
M. J. Cook ◽  
P. K. Wu ◽  
N. Patibandla ◽  
W. B. Hillig ◽  
J. B. Hudson
Keyword(s):  
Vapor Deposition ◽  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
Low Pressure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fiber Coating ◽  
Pressure Chemical ◽  
Substrate Temperatures ◽  
Carbon Concentrations

AbstractAluminum nitride films were deposited on Si (100) and sapphire (1102) substrates by low pressure chemical vapor deposition using the metalorganic precursor trisdimethylaluminum amide, [(CH3)2AlNH2]3. Depositions were carried out in a cold wall reactor with substrate temperatures between 500 and 700 °C and precursor temperatures between 50 and 80 °C. The films were analyzed by X-ray photoelectron spectroscopy, X-ray diffraction, optical microscopy and scanning electron microscopy. The films were generally smooth and adherent with colors ranging from transparent to opaque grey. Cracking and spallation were seen to occur at high film thickness. Deposition rates ranged from 20 to 300 Å/min and increased with both precursor and substrate temperature. Carbon concentrations were small, < 5 at. %, while oxygen concentrations were higher and showed a characteristic profile versus depth in the film. High temperature compatibility testing with sapphire/AlN/MoSi2 samples was carried out to determine film effectiveness as a fiber coating in a composite.

Trimethylamine Gallane as a Precursor to Cubic Gallium Nitride and Gallium Arsenide. Metal Hydride Chemical Vapor Deposition

1990 ◽  
Vol 204 ◽  
Author(s):  
Wayne L. Gladfelter ◽  
Jen-Wei Hwang ◽  
Everett C. Phillips ◽  
John F. Evans ◽  
Scott A. Hanson ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pressure Chemical ◽  
Elemental Arsenic

ABSTRACTCyclo-trigallazane, [H2GaNH2]3, is known to form bulk powders of the new cubic phase of gallium nitride upon pyrolysis. An explanation for this unusual example where the molecular structure of the precursor controls the crystal structure of the solid state product is presented. In a hot-wall atmospheric pressure chemical vapor deposition (CVD) reactor, arsine was found to react with TMAG to form films of polycrystalline GaAs which were characterized by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The growth rates for smooth films was 1-4 μm/h. In a low pressure CVD reactor, elemental arsenic vapor was also found to react with the TMAG to give GaAs thin films.

scholarly journals Comparison of Gas Sensing Properties of Reduced Graphene Oxide Obtained by Two Different Methods

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3175
Author(s):  
Sabina Drewniak ◽  
Marcin Procek ◽  
Roksana Muzyka ◽  
Tadeusz Pustelny
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Gas Sensing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sorption Method ◽  
Reduced Graphene ◽  
Gaseous Atmospheres

In this study, the sensitivity of reduced graphene oxide structures (rGO) to the action of selected gases (especially hydrogen, but also nitrogen dioxide and ammonia) was examined. Two sensing structures, based on rGO structures, obtained by different methods of oxidation (the modified Hummers, and the modified Tour’s method respectively), were investigated. We show here that the method used for the oxidation of rGO influences the sensitivity of the sensing structure during contact with various gaseous atmospheres. We performed our experiments in the atmosphere, containing hydrogen in a concentration range from 0 to 4% in nitrogen or synthetic air, both in dry and wet conditions. The temperature range was from 50 °C to 190 °C. Finally, we checked how the resistance of the samples changes when the other gases (NO2, NH3) appear in tested gas mixtures. The gas investigations were supplemented by the characterization of rGOs materials using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and N2 sorption method.

Novel Preparation and Characterization of Fe2O3/CNT Thin Films for Flammable Gas Sensors

2019 ◽  
Vol 947 ◽  
pp. 47-51
Author(s):  
Buaworn Chaitongrat ◽  
Sutichai Chaisitsak
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Gas Sensing ◽  
Chemical Vapor ◽  
Dry Process ◽  
Vapor Deposition Technique ◽  
Flammable Gas ◽  
Recovery Times ◽  
Response And Recovery

In this work, novel preparation for Fe2O3/CNT thin films was investigated. The Fe/CNT thin films were synthesized through vertical floating-catalyst chemical vapor deposition technique (FC-CVD) and subsequently annealed in air. The various annealing temperature to create Fe2O3 was examined and characterized by field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), Ultraviolet–visible spectroscopy (UV-Vis) and Raman spectroscopy. In addition, effect of wet/dry process on gas sensing of Fe2O3/CNTs was also investigated. The results suggest that the interfacial oxide layer helps to significantly improve LPG sensing performance with rapid response and recovery times. The proposed method can be considered as a promising approach for producing ultra-Fe2O3/CNT thin films that are appropriate for sensing application.

Characterization of Green Laser Crystallized GeSi Thin Films

2011 ◽  
Vol 1321 ◽  
Author(s):  
Balaji Rangarajan ◽  
Ihor Brunets ◽  
Peter Oesterlin ◽  
Alexey Y. Kovalgin ◽  
Jurriaan Schmitz
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Vapour ◽  
Green Laser ◽  
Laser Crystallization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Pressure Chemical

ABSTRACTGreen laser crystallization of a-Ge0.85Si0.15 films deposited using Low Pressure Chemical Vapour Deposition is studied. Large grains of 8x2 μm2 size were formed using a location-controlled approach. Characterization is done using Scanning Electron Microscopy, Atomic Force Microscopy, X-Ray Photoelectron Spectroscopy and X-Ray Diffraction.

scholarly journals Synthesis and Characterizations of 2D Platinum Diselenide

2020 ◽  
Vol 2 (1) ◽  
pp. 22
Author(s):  
Irnik Dionisiev ◽  
Vera Marinova ◽  
Krastyo Buchkov ◽  
Hristosko Dikov ◽  
Ivalina Avramova ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Large Scale ◽  
Strong Dependence ◽  
Chemical Vapor ◽  
Thickness Variation ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
X Ray

Platinum diselenide (PtSe2), which belongs to the transition metals dichalcogenide (TMDCs) class of 2D materials, is characterized with a transition from semimetal to semiconductor with a thickness variation from bulk to monolayer and found in versatile applications especially in sensors and mid-infrared detectors. In this study we report the large-scale synthesis of PtSe2 layers by thermally assisted selenization of pre-deposited platinum films in a horizontal quartz-tube Chemical Vapor Deposition (CVD) reactor. Raman spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) are used for characterization of the obtained 2D PtSe2. It is observed that the Raman spectra of PtSe2 show strong dependence on the thickness (Pt deposition time). XPS analysis was applied to examine the chemical compositions in order to assess the quality of the synthesized PtSe2 films. All the studied properties reveal great potential to obtain continuous layers with a controlled thickness and composition and further potential for integration in functional heterostructures for future nanoelectronic and optoelectronic devices.

AlxGa1-xN-Based Materials and Heterostructures

1996 ◽  
Vol 449 ◽  
Author(s):  
P. Kung ◽  
A. Saxler ◽  
D. Walker ◽  
X. Zhang ◽  
R. Lavado ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Bragg Reflectors ◽  
X Ray Diffraction ◽  
Chemical Vapor Deposition Growth ◽  
X Ray ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
Dimensional Electron Gas ◽  
P Type

ABSTRACTWe present the metalorganic chemical vapor deposition growth, n-type and p-type doping and characterization of AlxGa1-xN alloys on sapphire substrates. We report the fabrication of Bragg reflectors and the demonstration of two dimensional electron gas structures using AlxGa1-xN high quality films. We report the structural characterization of the AlxGa1-xN / GaN multilayer structures and superlattices through X-ray diffraction and transmission electron microscopy. A density of screw and mixed threading dislocations as low as 107 cm-2 was estimated in AlxGa1-xN / GaN structures. The realization of AlxGa1-xN based UV photodetectors with tailored cut-off wavelengths from 365 to 200 nm are presented.

scholarly journals Fabrication and Characterization of Al/NiO Energetic Nanomultilayers

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
YiChao Yan ◽  
Wei Shi ◽  
HongChuan Jiang ◽  
Jie Xiong ◽  
WanLi Zhang ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Total Thickness ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
Metallic Oxide ◽  
Promising Candidate ◽  
X Ray ◽  
Thermal Boundary Conductance ◽  
Fabrication And Characterization

The redox reaction between Al and metallic oxide has its advantage compared with intermetallic reaction and Al/NiO nanomutlilayers are a promising candidate for enhancing the performance of energetic igniter. Al/NiO nanomutlilayers with different modulation periods are prepared on alumina substrate by direct current (DC) magnetron sputtering. The thicknesses of each period are 250 nm, 500 nm, 750 nm, 1000 nm, and 1500 nm, respectively, and the total thickness is 3 μm. The X-ray diffraction (XRD) and scanning electron microscope (SEM) results of the as-deposited Al/NiO nanomutlilayers show that the NiO films are amorphous and the layered structures are clearly distinguished. The X-ray photoelectron spectroscopy (XPS) demonstrates that the thickness of Al2O3increases on the side of Al monolayer after annealing at 450°C. The thermal diffusion time becomes greater significantly as the amount of thermal boundary conductance across the interfaces increases with relatively smaller modulation period. Differential scanning calorimeter (DSC) curve suggests that the energy release per unit mass is below the theoretical heat of the reaction due to the nonstoichiometric ratio between Al and NiO and the presence of impurities.

Preparation and Characterization of γ-Fe2O3-ZnFe2O4 Composite Nanoparticles

2013 ◽  
Vol 873 ◽  
pp. 152-157
Author(s):  
Long Long Chen ◽  
Jun Ming Li ◽  
Xiao Min Gong ◽  
Jian Li
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Species ◽  
Composite Nanoparticles ◽  
X Ray Diffraction ◽  
Ferrite Core ◽  
Phase Synthesis ◽  
X Ray ◽  
Transmission Electron ◽  
Chemically Induced

Using a chemically induced transition in an FeCl2 solution, γ-Fe2O3 nanoparticles can be prepared from an amorphous precursor composed of FeOOH and Mg (OH)2. Surface modification by adding ZnCl2 during liquid-phase synthesis was attempted. The magnetization, morphology, crystal structure, and chemical species of as-prepared samples were characterized by vibrating sample magnetometer (VSM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray energy-dispersive spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). The experimental results showed that the surface of the γ-Fe2O3 nanoparticles can be modified by adding ZnCl2 to form composite nanoparticles with a γ-Fe2O3/ZnFe2O4 ferrite core coated with Zn (OH)2 and absorbed FeCl36H2O; this modification can be enhanced by additional NaOH.

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