Control of Chemical Reactions for Growth of Crystalline Si at Low Substrate Temperature

1989 ◽  
Vol 164 ◽  
Author(s):  
Isamu Shimizu ◽  
Jun-Ichi Hanna ◽  
Hajime Shirai
Keyword(s):  
Low Temperature ◽  
Substrate Temperature ◽  
Chemical Reactions ◽  
Systematic Study ◽  
Atomic Hydrogen ◽  
Network Structures ◽  
Control Of Flow ◽  
Selection Of

AbstractA systematic study has been made on the formation of Si-network of amorphous(a-), microcrystalline(μc-) and epitaxial (epi)-Si prepared by Plasma-Enhaced (PE-) CVD under control of flow of atomic hydrogen. The control of the Si-network structures requires a deliberate selection of the precursor, i.e., SiHn (n≤53) and SiFnHm (n+m≤53), as well as an intentional acceleration of the chemical reactions for the propagation of Si-network in the vicinity of the growing surface by impinging of atomic hydrogen. A plausible interpretation was given to the growing mechanism of c-Si at low temperature.

Low-Temperature Post-Oxidation Annealing Using Atomic Hydrogen Radicals Generated by High-Temperature Catalyzer for Improvement in Reliability of Thermal Oxides on 4H-SiC

2006 ◽  
Vol 527-529 ◽  
pp. 999-1002
Author(s):  
Junji Senzaki ◽  
Atsushi Shimozato ◽  
Kenji Fukuda
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Atomic Hydrogen ◽  
High Reliability ◽  
Hydrogen Atmosphere ◽  
Exposed Sample ◽  
New Apparatus ◽  
Hydrogen Radical ◽  
Hydrogen Radicals ◽  
Sic Wafer

Low-temperature post-oxidation annealing (POA) process of high-reliability thermal oxides grown on 4H-SiC using new apparatus that generates atomic hydrogen radicals by high-temperature catalyzer has been investigated. Atomic hydrogen radicals were generated by thermal decomposition of H2 gas at the catalyzer surface heated at high temperature of 1800°C, and then exposed to the sample at 500°C in reactor pressure of 20 Pa. The mode and maximum values of field-to-breakdown are 11.0 and 11.2 MV/cm, respectively, for the atomic hydrogen radical exposed sample. In addition, the charge-to-breakdown at 63% cumulative failure of the thermal oxides for atomic hydrogen radical exposed sample was 0.51 C/cm2, which was higher than that annealed at 800°C in hydrogen atmosphere (0.39 C/cm2). Consequently, the atomic hydrogen radical exposure at 500°C has remarkably improved the reliability of thermal oxides on 4H-SiC wafer, and is the same effect with high-temperature hydrogen POA at 800°C.

scholarly journals Advances in Cryochemistry: Mechanisms, Reactions and Applications

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 750
Author(s):  
Lu-Yan An ◽  
Zhen Dai ◽  
Bin Di ◽  
Li-Li Xu
Keyword(s):  
Low Temperature ◽  
Chemical Reactions ◽  
Common Sense ◽  
Reaction Rate ◽  
Concentration Effect ◽  
Biological Products ◽  
Freeze Concentration ◽  
New Strategy ◽  
The 1960S

It is counterintuitive that chemical reactions can be accelerated by freezing, but this amazing phenomenon was discovered as early as the 1960s. In frozen systems, the increase in reaction rate is caused by various mechanisms and the freeze concentration effect is the main reason for the observed acceleration. Some accelerated reactions have great application value in the chemistry synthesis and environmental fields; at the same time, certain reactions accelerated at low temperature during the storage of food, medicine, and biological products should cause concern. The study of reactions accelerated by freezing will overturn common sense and provide a new strategy for researchers in the chemistry field. In this review, we mainly introduce various mechanisms for accelerating reactions induced by freezing and summarize a variety of accelerated cryochemical reactions and their applications.

Electrical Characterization of Low Temperature GaAs Layers, and Observation of the Extremely Large Carrier Concentrations in Undoped Material

1991 ◽  
Vol 241 ◽  
Author(s):  
Bijan Tadayon ◽  
Mohammad Fatemi ◽  
Saied Tadayon ◽  
F. Moore ◽  
Harry Dietrich
Keyword(s):  
Molecular Beam Epitaxy ◽  
Low Temperature ◽  
Substrate Temperature ◽  
Molecular Beam ◽  
Electrical Characterization ◽  
Physical Characteristics ◽  
Hall Measurements ◽  
Undoped Material ◽  
Low Temperature Gaas

ABSTRACTWe present here the results of a study on the effect of substrate temperature, Ts, on the electrical and physical characteristics of low temperature (LT) molecular beam epitaxy GaAs layers. Hall measurements have been performed on the asgrown samples and on samples annealed at 610 °C and 850 °C. Si implantation into these layers has also been investigated.

scholarly journals On apparent barrier-free reactions

2020 ◽  
Vol 3 (1) ◽  
pp. 3-8
Author(s):  
Maikel Ballester
Keyword(s):  
Low Temperature ◽  
Chemical Reactions ◽  
Rate Constant ◽  
Kinetic Models ◽  
Rate Coefficient ◽  
Minimum Energy ◽  
Temperature Limit ◽  
Rate Coefficients ◽  
Minimum Energy Path ◽  
Full Dimension

Rate coefficients of bi-molecular chemical reactions are fundamental for kinetic models. The rate coefficient dependence on temperature is commonly extracted from the analyses of the reaction minimum energy path. However, a full dimension study of the same reaction may suggest a different asymptotic low-temperature limit in the rate constant than the obtained from the energetic profile.

scholarly journals Low-Temperature Chemical Vapor Deposition Growth of MoS2 Nanodots and Their Raman and Photoluminescence Profiles

2021 ◽  
Vol 3 ◽  
Author(s):  
Larionette P. L. Mawlong ◽  
Ravi K. Biroju ◽  
P. K. Giri
Keyword(s):  
Chemical Vapor Deposition ◽  
Low Temperature ◽  
Substrate Temperature ◽  
Vapor Deposition ◽  
Photoelectron Spectroscopy ◽  
Flexible Substrate ◽  
Chemical Vapor ◽  
Structural Defects ◽  
Chemical Vapor Deposition Growth ◽  
Raman Modes

We report on the growth of an ordered array of MoS2 nanodots (lateral sizes in the range of ∼100–250 nm) by a thermal chemical vapor deposition (CVD) method directly onto SiO2 substrates at a relatively low substrate temperature (510–560°C). The temperature-dependent growth and evolution of MoS2 nanodots and the local environment of sulfur-induced structural defects and impurities were systematically investigated by field emission scanning electron microscopy, micro-Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) techniques. At the substrate temperature of 560°C, we observed mostly few-layer MoS2, and at 510°C, multilayer MoS2 growth, as confirmed from the Raman line shape analysis. With reduced substrate temperature, the density of MoS2 nanodots decreases, and layer thickness increases. Raman studies show characteristic Raman modes of the crystalline MoS2 layer, along with two new Raman modes centered at ∼346 and ∼361 cm−1, which are associated with MoO2 and MoO3 phases, respectively. Room temperature photoluminescence (PL) studies revealed strong visible PL from MoS2 layers, which is strongly blue-shifted from the bulk MoS2 flakes. The strong visible emission centered at ∼ 658 nm signifies a free excitonic transition in the direct gap of single-layer MoS2. Position-dependent PL profiles show excellent uniformity of the MoS2 layers for samples grown at 540 and 560°C. These results are significant for the low-temperature CVD growth of a few-layer MoS2 dots with direct bandgap photoluminescence on a flexible substrate.

Low Temperature Deposited High Quality ITO Films Prepared by E-Beam Evaporation

1990 ◽  
Vol 187 ◽  
Author(s):  
C. S. Chang ◽  
J. C. Wang ◽  
L. C. Kuo
Keyword(s):  
Electron Beam ◽  
Low Temperature ◽  
Substrate Temperature ◽  
Optimal Condition ◽  
Deposition Rate ◽  
Oxygen Pressure ◽  
Electron Beam Evaporation ◽  
Film Properties ◽  
High Quality ◽  
Ito Films

AbstractAn electron beam evaporation method has been used to prepare tin doped indium oxide (ITO) films with 95 wt.% In2O3 and 5 wt.% SnO2 in an oxygen atmosphere. It was found that the deposition rate and oxygen pressure strongly influence the film properties when the substrate temperature was lower than 200°C. In an optimal condition, highly transparent (transmittance ˜ 90% at wavelength 570 nm) and conductive (resistivity – 3×10−4Ω-cm) films of thickness around 2000 Å at substrate temperature as low as 180°C can be obtained.

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