Properties Of crystalline 3C-SIC Grown From Methyl Trichlorosilane

1994 ◽  
Vol 339 ◽  
Author(s):  
W. J. Moore ◽  
R. Kaplan ◽  
J. A. Freitas ◽  
Y. M. Altaiskii ◽  
V. L. Zuev ◽  
...  
Keyword(s):  
Activation Energy ◽  
Low Temperature ◽  
Effective Mass ◽  
Nitrogen Concentration ◽  
Excitation Spectra ◽  
High Quality ◽  
Temperature Conductivity ◽  
Ir Transmission ◽  
Temperature Electron ◽  
Cubic Silicon Carbide

ABSTRACTCubic silicon carbide grown by thermal decomposition of methyl trichlorosilane in hydrogen has been studied in infrared (IR) transmission, cyclotron resonance (CR), and photoluminescence (PL). Sample characteristics include: The nitrogen concentration, determined from CR and IR can be of the order of 1015 cm-3 or less. Ionized impurity concentrations determined from the linewidths of CR and IR spectra can be less than 7 × 1014 cm-3. Low temperature electron mobilities from CR are near 105 cm2 v-1 s-1. Carrier freeze-out is consistent with either uncompen-sated donors with activation energy near 50 meV or heavily compensated donors with 20 meV activation energy. The latter choice, however, is excluded by the low ionized impurity concentration. These high quality samples show little or no evidence of the apparently shallow (< ∼20 meV) donor which usually dominates the low temperature conductivity of 3C-SiC grown on Si. Nitrogen donor excitation spectra are in excellent agreement with effective mass theory. Only nitrogen donors at 54.2 meV and an unidentified effective-mass donor at 47.8 meV are observed. If material with the characteristics described above can be reliably reproduced then there is substantial expectation that high quality electronic devices based on 3C-SiC can be fabricated.

Study on Low Temperature Conduction Mechanism of Al Doped ZnO/SiO2/ P-Si Heterojunction

2021 ◽  
Vol 904 ◽  
pp. 363-368
Author(s):  
Xiao Yan Zhou ◽  
Bang Sheng Yin
Keyword(s):  
Activation Energy ◽  
Impedance Spectroscopy ◽  
Low Temperature ◽  
Grain Boundaries ◽  
Ac Conductivity ◽  
Spray Pyrolysis Method ◽  
Temperature Conductivity ◽  
Calculated Activation Energy ◽  
Doped Zno ◽  
Temperature Conduction

The 3 at% Al doped ZnO thin films were deposited on p-Si substrate with a native SiO2 layer by spray pyrolysis method. Low temperature conduction behaviors were studied by analysis of impedance spectroscopy and low temperature ac conductivity. The results of impedance spectroscopy showed that the grain boundaries contributed to the resistivity of Al doped ZnO/SiO2/p-Si heterojunction. The calculated activation energy was 0.073 eV for grain boundaries. The equivalent circuit to demonstrate the electrical properties of Al doped ZnO/SiO2/p-Si heterojunction was a series connection of two parallel combination circuits of a resistor and a universal capacitor. Low temperature ac conductivity measurements indicated that the conductivity increased with temperature. Low temperature conductivity mechanism was electron conductivity, and the activation energy was 0.086 eV.

Amorphous Si1-YGeY:H, F films obtained by Low Frequency PECVD for uncooled microbolometers

2004 ◽  
Vol 808 ◽  
Author(s):  
R. Ambrosio ◽  
A. Torres ◽  
A. Kosarev ◽  
A. S. Abramov ◽  
A. Heredia ◽  
...  
Keyword(s):  
Activation Energy ◽  
Room Temperature ◽  
Solid Phase ◽  
Low Frequency ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
Sensing Material ◽  
Temperature Dependence Of Conductivity ◽  
Ir Transmission ◽  
High Absorption

ABSTRACTIn this work, we report the composition, optical, and electrical properties of a- Si1-YGeY: H, F films to be used as sensing layer in uncooled microbolometers. The a-Si1-YGeY films where Y is Ge content in solid phase were deposited by low frequency PECVD from SiH4 and GeF4 feed gases, and H2 and Ar were used for dilution. The film composition, IR transmission and temperature dependence of conductivity were measured. The reduction of conductivity activation energy from 0.86 eV to 0.39 eV and the increase of room temperature conductivity from 1x10−9 to 2.1×10−3 Ohm−1cm−1 were observed with the change of Y from 0 (Si) to 1(Ge). These results demonstrate this material to be a good candidate as a sensing material in uncooled micro-bolometers, due to its high absorption in the range of λ = 10-13 μm, its relatively high activation energy, Ea=0.4 eV, consequently, a high temperature coefficient of resistance (TCR), and moderate resistivity at room temperature.

scholarly journals The electrical conductivity of stannous sulphide

1945 ◽  
Vol 184 (996) ◽  
pp. 83-101 ◽  
Keyword(s):  
Activation Energy ◽  
Low Temperature ◽  
Present Theory ◽  
Surface Layers ◽  
Considerable Decrease ◽  
Temperature Conductivity ◽  
Full Band ◽  
Ordinary Temperature ◽  
Intrinsic Conduction ◽  
Positive Holes

The conductivity of stannous sulphide has been measured between the ordinary temperature and 400° C, and follows the expression K T = A 1 e - E 1 / kT + A 2 e - E 2 / kT . The low-temperature conductivity has been studied with particular reference to the effect of chemical treatment calculated to change any deviations from ideal stoich iometric composition. Treatment with hydrogen at temperatures below those at which reduction to tin can occur brings about a considerable decrease in conductivity; exposure to oxygen or to hydrogen sulphide restores the conductivity. The low-temperature conductivity is attributable to a stoichiometric excess of non-metal in the lattice, the current being transported by a corresponding number of positive holes. From the rate of diminution or restoration of conductivity, the positive holes must be located in the surface layers of atoms of the crystallites. The changes in conductivity resulting from changes in the stoichiometric defect arise almost entirely through the change in the activation energy of the conduction process, E 1 . Although not considered in the present theory of semiconductors, both E 1 and the electronic mobility are functions of the concentration of conducting centres. The high-temperature conductivity is attributed to the intrinsic conduction of the lattice, and indicates the existence of a conduction band about 1·2 eV above the full band.

Voids-Free 3C-SiC/Si Interface for High Quality Epitaxial Layer

2016 ◽  
Vol 858 ◽  
pp. 159-162 ◽  
Author(s):  
Ruggero Anzalone ◽  
Nicolò Piluso ◽  
Riccardo Reitano ◽  
Alessandra Alberti ◽  
Patrick Fiorenza ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Low Temperature ◽  
Epitaxial Growth ◽  
Buffer Layer ◽  
Epitaxial Layer ◽  
High Quality ◽  
Wafer Curvature ◽  
Carbonization Process ◽  
Cubic Silicon Carbide ◽  
Sic Film

A study of the carbonization process and of a low temperature buffer layer on the Cubic Silicon Carbide (3C-SiC) epitaxial growth has been reported in this work. From this study it has been evidenced the importance of the C/H2 ratio and of the buffer layer process on the voids formation at the 3C-SiC/Si interface. From our study, the influence of the voids the wafer curvature is highlighted. It has been observed that decreasing the density of these voids, decreases the stress of the 3C-SiC film; consequently, the wafer curvature is reduced.

Low-Temperature Electron Spectra of Impurities in Naphtalene Crystals

2014 ◽  
Vol 59 (3) ◽  
pp. 209-214
Author(s):  
N.D. Curmei ◽  
◽  
G.V. Klishevich ◽  
V.I. Melnyk ◽  
◽  
...  
Keyword(s):  
Low Temperature ◽  
Electron Spectra ◽  
Temperature Electron

Pt-Pd Nanoalloy for the Unprecedented Activation of Carbon-Fluorine Bond at Low Temperature

2019 ◽  
Author(s):  
Raghu Nath Dhital ◽  
keigo nomura ◽  
Yoshinori Sato ◽  
Setsiri Haesuwannakij ◽  
Masahiro Ehara ◽  
...  
Keyword(s):  
Activation Energy ◽  
Low Temperature ◽  
Dft Calculations ◽  
Bond Activation ◽  
Mild Conditions ◽  
Selective Transformation ◽  
Rate Determining Step ◽  
Highly Active ◽  
Harsh Conditions ◽  
Reaction Profile

Carbon-Fluorine (C-F) bonds are considered the most inert organic functionality and their selective transformation under mild conditions remains challenging. Herein, we report a highly active Pt-Pd nanoalloy as a robust catalyst for the transformation of C-F bonds into C-H bonds at low temperature, a reaction that often required harsh conditions. The alloying of Pt with Pd is crucial to activate C-F bond. The reaction profile kinetics revealed that the major source of hydrogen in the defluorinated product is the alcoholic proton of 2-propanol, and the rate-determining step is the reduction of the metal upon transfer of the <i>beta</i>-H from 2-propanol. DFT calculations elucidated that the key step is the selective oxidative addition of the O-H bond of 2-propanol to a Pd center prior to C-F bond activation at a Pt site, which crucially reduces the activation energy of the C-F bond. Therefore, both Pt and Pd work independently but synergistically to promote the overall reaction

TECHNOLOGICAL ASPECTS OF HIGH QUALITY RAW MATERIAL OBTAINING FOR PECTIN PRODUCTION

1970 ◽  
pp. 47-50
Author(s):  
I. A. Ilina ◽  
I. A. Machneva ◽  
E. S. Bakun
Keyword(s):  
Raw Materials ◽  
Thermal Characteristics ◽  
Environmental Safety ◽  
Raw Material ◽  
High Quality ◽  
Temperature Conductivity ◽  
Drying Temperature ◽  
Plant Raw Materials ◽  
Gel Forming Ability

  The article is devoted to the study of the chemical composition, physical and thermal-pfysical characteristics of damp apple pomaces and the identifying patterns of influence of drying temperature the functional composition and gel-forming ability of pectin. The research is aimed at obtaining initial data for the subsequent calculation of the main technological, hydro-mechanical, thermal, structural and economic characteristics of devices for drying the plant raw materials, ensuring the environmental safety and high quality of pectin-containing raw materials, the reducing heat and energy costs. As a result of the study of the thermal characteristics of apple pomaces, the critical points (temperature conductivity – 16.5 x 10-8 m2/s, thermal conductivity – 0.28 W/m K, heat capacity – 1627 j/(kg K)) at a humidity of 56 % are determined, which characterizing the transition from the extraction of weakly bound moisture to the extraction of moisture with strong bonds (colloidal, adsorption). It was found that the pomaces obtained from apples of late ripening have a higher content of solids (21-23 %), soluble pectin and protopectin (2.5-4.5 %). Dried pomaces obtained from apple varieties of late ripening contain up to 25 % pectin, which allow us to recommend them as a source of raw materials for the production of pectin. The optimum modes of preliminary washing of raw materials are offered, allowing to the remove the ballast substances as much as possible. It is established that when the drying temperature increases, the destructive processes are catalyzed: the strength of the pectin jelly and the uronide component and the degree of pectin esterification are reduced. The optimum drying temperature of damp apple pomaces is 80 0C, at which the quality of pectin extracted from the dried raw materials is maintained as much as possible. It is shown that the most effective for the pectin production is a fraction with a particle size of 3-5 mm, which allow us to extract up to 71 % of pectin from raw materials.

AISI TYPE P20

Alloy Digest ◽  
1982 ◽  
Vol 31 (1) ◽  
Keyword(s):  
Low Temperature ◽  
Tool Steel ◽  
Die Casting ◽  
Heat Treating ◽  
High Quality ◽  
Medium Carbon ◽  
Casting Alloys ◽  
Steel Mills ◽  
Aisi Type ◽  
Quality Tool

Abstract AISI Type P20 is a chromium-molybdenum tool steel of medium carbon content. It usually is supplied in the prehardened condition (about 300 Brinell) so that the cavity can be machined and the mold or die placed directly in service; however, for some uses further treatments are employed. It is produced to high-quality tool-steel standards to permit a high luster to be achieved on the surface of the polished die cavity. P20 is used for molds for plastics and for die-casting dies for zinc and other low-temperature casting alloys. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on forming, heat treating, and machining. Filing Code: TS-393. Producer or source: Tool steel mills.

Sign in / Sign up

Export Citation Format

Share Document