Size-selective and High-yield Nanocrystal Growth of PbTe Compounds Using a Chemical Vapor Deposition Technique

2005 ◽  
Vol 886 ◽  
Author(s):  
B. Zhang ◽  
Nicholas Gothard ◽  
Jian He ◽  
Daniel Thompson ◽  
Terry M. Tritt
Keyword(s):  
Chemical Vapor ◽  
Good Control ◽  
Atomic Ratio ◽  
High Yield ◽  
Chemical Vapor Transport ◽  
Selective Precipitation ◽  
Lattice Constants ◽  
Nanocrystal Growth ◽  
Vapor Deposition Technique ◽  
Xrd Patterns

ABSTRACTThe nanocrystals of PbTe and related compounds (Pb1−xSnxTe, PbTe1−xSex), differing by size and composition, have been synthesized using a chemical vapor transport (CVD) technique. The size–selective precipitation mechanism relying on the variation of heating temperatures, Ar flow rates and admixture with Au particles, enables a relatively good control of particle size distribution. In addition, the doping ratios of those nanocrystals are readily modified by changing the atomic ratio in the raw starting materials. Subsequently, a yield of hundreds of milligrams of nanocrystals which exhibit narrow size distributions at 100 nm, 300 nm and 600 nm and controllable composition have been obtained. XRD patterns taken on the PbTe samples show sharp, which indicate good crystallinity of samples. According to the shift of the Bragg reflections, the lattice constants of (Sn / Se) doped PbTe change with the variation of the doping ratios.

Multiple Donors in Zinc Oxide Substrates

2002 ◽  
Vol 719 ◽  
Author(s):  
K. Thonke ◽  
N. Kerwien ◽  
A. Wysmolek ◽  
M. Potemski ◽  
A. Waag ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Chemical Vapor ◽  
Binding Energies ◽  
Vapor Transport ◽  
Chemical Vapor Transport ◽  
Oxide Substrates ◽  
Multiple Donors ◽  
Major Donors ◽  
Available Zinc ◽  
Transport Technique

AbstractWe investigate by photoluminescence (PL) nominally undoped, commercially available Zinc Oxide substrates (from Eagle Picher) grown by seeded chemical vapor transport technique in order to identify residual donors and acceptors. In low temperature PL spectra the dominant emission comes from the decay of bound exciton lines at around 3.36 eV. Zeeman measurements allow the identification of the two strongest lines and some weaker lines in-between as donorrelated. From the associated two-electron satellite lines binding energies of the major donors of 48 meV and 55 meV, respectively, can be deduced.

scholarly journals Synthesis of Boron-Doped Silicon Film Using Hot Wire Chemical Vapor Deposition Technique

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 237
Author(s):  
M. Abul Hossion ◽  
B. M. Arora
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Polycrystalline Silicon ◽  
Silicon Film ◽  
Chemical Vapor ◽  
Hot Wire ◽  
Deposition Technique ◽  
Boron Doped ◽  
Vapor Deposition Technique ◽  
Polycrystalline Silicon Film

Boron-doped polycrystalline silicon film was synthesized using hot wire chemical vapor deposition technique for possible application in photonics devices. To investigate the effect of substrate, we considered Si/SiO2, glass/ITO/TiO2, Al2O3, and nickel tungsten alloy strip for the growth of polycrystalline silicon films. Scanning electron microscopy, optical reflectance, optical transmittance, X-ray diffraction, and I-V measurements were used to characterize the silicon films. The resistivity of the film was 1.3 × 10−2 Ω-cm for the polycrystalline silicon film, which was suitable for using as a window layer in a solar cell. These films have potential uses in making photodiode and photosensing devices.

scholarly journals Evolution of reduction process from tungsten oxide to ultrafine tungsten powder via hydrogen

2021 ◽  
Vol 40 (1) ◽  
pp. 171-177
Author(s):  
Yue Wang ◽  
Ben Fu Long ◽  
Chun Yu Liu ◽  
Gao An Lin
Keyword(s):  
Surface Morphology ◽  
Tungsten Oxide ◽  
Tungsten Powder ◽  
Reduction Process ◽  
Chemical Vapor ◽  
Transition Process ◽  
Vapor Transport ◽  
Fibrous Structure ◽  
Chemical Vapor Transport ◽  
Oxide Particles

Abstract Herein, the evolution of reduction process of ultrafine tungsten powder in industrial conditions was investigated. The transition process of morphology and composition was examined via SEM, XRD, and calcination experiments. The results show that the reduction sequence of WO2.9 was WO2.9 → WO2.72 → WO2 → W on the surface, but WO2.9 → WO2 → W inside the oxide particles. With the aid of chemical vapor transport of WO x (OH) y , surface morphology transformed into rod-like, star-shaped cracking, floret, irregularly fibrous structure, and finally, spherical tungsten particles.

scholarly journals Silica Layer Used in Sensor Fabrication from a Low-Temperature Silane-Free Procedure

Chemosensors ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 32
Author(s):  
Pei-Cheng Jiang ◽  
Yu-Ting Chow ◽  
Chi-Wei Chien ◽  
Cheng-Hsun-Tony Chang ◽  
Chii-Ruey Lin
Keyword(s):  
Room Temperature ◽  
Chemical Vapor ◽  
Industrial Safety ◽  
Silica Layer ◽  
Silica Films ◽  
Sensor Fabrication ◽  
Vapor Deposition Technique ◽  
Safety Design ◽  
Biogenic Polyamines ◽  
Si Wafer

Silica (SiO2, silicon dioxide—a dielectric layer commonly used in electronic devices) is widely used in many types of sensors, such as gas, molecular, and biogenic polyamines. To form silica films, core shell or an encapsulated layer, silane has been used as a precursor in recent decades. However, there are many hazards caused by using silane, such as its being extremely flammable, the explosive air, and skin and eye pain. To avoid these hazards, it is necessary to spend many resources on industrial safety design. Thus, the silica synthesized without silane gas which can be determined as a silane-free procedure presents a clean and safe solution to manufactures. In this report, we used the radio frequency (rf = 13.56 MHz) plasma-enhanced chemical vapor deposition technique (PECVD) to form a silica layer at room temperature. The silica layer is formed in hydrogen-based plasma at room temperature and silane gas is not used in this process. The substrate temperature dominates the silica formation, but the distance between the substrate and electrode (DSTE) and the methane additive can enhance the formation of a silica layer on the Si wafer. This silane-free procedure, at room temperature, is not only safer and friendlier to the environment but is also useful in the fabrication of many types of sensors.

scholarly journals Impedance Spectroscopic Study of Nickel Sulfide Nanostructures Deposited by Aerosol Assisted Chemical Vapor Deposition Technique

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1105
Author(s):  
Sadia Iram ◽  
Azhar Mahmood ◽  
Muhammad Fahad Ehsan ◽  
Asad Mumtaz ◽  
Manzar Sohail ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Nickel Sulfide ◽  
Variable Temperature ◽  
Complex Impedance ◽  
Equivalent Circuit Model ◽  
Chemical Vapor ◽  
Relaxation Processes ◽  
Impedance Plot ◽  
Vapor Deposition Technique

This research aims to synthesize the Bis(di-isobutyldithiophosphinato) nickel (II) complex [Ni(iBu2PS2)] to be employed as a substrate for the deposition of nickel sulfide nanostructures, and to investigate its dielectric and impedance characteristics for applications in the electronic industry. Various analytical tools including elemental analysis, mass spectrometry, IR, and TGA were also used to further confirm the successful synthesis of the precursor. NiS nanostructures were grown on the glass substrates by employing an aerosol assisted chemical vapor deposition (AACVD) technique via successful decomposition of the synthesized complex under variable temperature conditions. XRD, SEM, TEM, and EDX methods were well applied to examine resultant nanostructures. Dielectric studies of NiS were carried out at room temperature within the 100 Hz to 5 MHz frequency range. Maxwell-Wagner model gave a complete explanation of the variation of dielectric properties along with frequency. The reason behind high dielectric constant values at low frequency was further endorsed by Koops phenomenological model. The efficient translational hopping and futile reorientation vibration caused the overdue exceptional drift of ac conductivity (σac) along with the rise in frequency. Two relaxation processes caused by grains and grain boundaries were identified from the fitting of a complex impedance plot with an equivalent circuit model (Rg Cg) (Rgb Qgb Cgb). Asymmetry and depression in the semicircle having center present lower than the impedance real axis gave solid justification of dielectric behavior that is non-Debye in nature.

In situ formation of highly exposed NiPS3 nanosheets on nickel foam as an efficient 3D electrocatalyst for overall water splitting

2021 ◽  
Author(s):  
Liang Fang ◽  
Yanping Xie ◽  
Peiyin Guo ◽  
Jingpei Zhu ◽  
Shuhui Xiao ◽  
...  
Keyword(s):  
Water Splitting ◽  
Nickel Foam ◽  
Chemical Vapor ◽  
Bifunctional Catalyst ◽  
Vapor Transport ◽  
Chemical Vapor Transport ◽  
Overall Water Splitting ◽  
One Step ◽  
Transport Method

Vertical NiPS3 nanosheets in situ grown on conducting nickel foam were fabricated by a facile one-step chemical vapor transport method and used as an efficient bifunctional catalyst for overall water splitting.

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