Selectivity Mechanisms in Low Temperature (<950°C) Selective Silicon Epitaxy

1992 ◽  
Vol 259 ◽  
Author(s):  
J.T. Fitch ◽  
D.J. Denning
Keyword(s):  
Low Temperature ◽  
Gas Phase ◽  
Flow Rate ◽  
Thermodynamic Modelling ◽  
Silicon Epitaxy ◽  
Species Selectivity ◽  
Process Pressure

ABSTRACTLow temperature selective silicon epitaxy was studied over a range of process pressures and HCI flows using a SiH2Cl2/HCl/H2 based chemistry. Thermodynamic modelling was carried out with the aid of the SOLGAS program to investigate the effect of process pressure, HCI flow rate, and leaks on the distribution of gas phase species. Selectivity results are interpreted in terms of the defect microchemistry on SiO2 surfaces.

Low Temperature Si Homoepitaxy by a Reactive CVD with a SiH4/F2 Mixture

2009 ◽  
Vol 1153 ◽  
Author(s):  
Akihisa Minowa ◽  
Michio Kondo
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Substrate Temperature ◽  
Gas Phase ◽  
Deposition Rate ◽  
Flow Rate ◽  
Exothermic Reaction ◽  
Phase Reaction ◽  
Single Crystalline ◽  
Gas Phase Reaction

AbstractSingle crystalline Si thin films on insulating substrates (SOI) have a variety of potential applications to such as high mobility TFT and to high efficiency and low cost solar cells. Since the SOI is limited to a thin layer, it is needed to develop a low temperature epitaxial growth technology to form active layers thicker than several micorns at low temperatures. The purpose of this study is to develop a deposition technique of single crystalline Si thin films by a reactive CVD method [1] at temperatures less than 600○C utilizing gas-phase reaction (SiH4, F2). Deposition of Si films was performed on a single crystalline Si (100) wafer. Substrate-temperature was varied between 100 and 700○C, reaction-pressure 1 and 500mTorr, flow-rate between SiH4/F2 = 1/1 and 1/3, and the geometry of the substrate and the gas-outlet were optimized. First, it was found that deposition rate was sensitive to the distance between the gas-outlet and the substrate and to the total pressure. For four different combinations of pressures, 250 and 500 mTorr and distances, 50 and 150 mm. The deposition took place only for the combination of 500 mTorr and 50 mm, and otherwise the deposition rate was significantly lower or etching of Si wafer was observed. The deposition rate for gas flow ratio, SiH4/F2 of 1/1 was 1.7 nm/s at a substrate-temperature of 400○C, while for higher F2 flow rate ratio, SiH4/F2 = 1/2 and 1/3, the deposition rates were 8.3×10-3 nm/s and etching, respectively. Raman measurements show that crystallinity depends on the substrate-temperature; broad amorphous signal appears at 300, microcrystalline signal at 300 and 500○C and sharp crystalline at 400○C. RHEED observation shows a halo-pattern of amorphous-Si at 200○C, a mixed pattern of streak and spot without 2×1 superstructure at 300○C, a 2×1 streak-pattern at 400○C and a spot-pattern at 500○C. The reason of the narrow temperature window for epitaxial layer is a characteristic feature of low temperature epitaxy as reported before [2]. It is noteworthy the deposition rate of epitaxy obtained in this work is quite high, 1.7 nm/s even at 400○C. These observations are ascribed to the gas phase reaction between SiH4 and F2 and successive surface reactions. The SiH4 and F2 cause an exothermic reaction in the gaseous phases to generate radicals such as SiHx, H and F. The SiHx acts as a film precursor and others act as etchant. Under the conditions which radical density ratio SiHx/F increases, therefore, the deposition rate decreases or etching occurs. The material properties also will be discussed in relation to the growth mechanism. [1]J. Hanna et al., J. Non-Crst. Solids 114 (1989) 172-174 [2]T. Kitagawa, M. Kondo et al, Appl. Surf. Sci. 159-160 (2000) 30-34

Aqueous Benzene Oxidation in Low-Temperature Plasma of Pulsed Corona Discharge

2016 ◽  
Vol 19 (2) ◽  
Author(s):  
Iakov Kornev ◽  
Sergei Preis
Keyword(s):  
Low Temperature ◽  
Corona Discharge ◽  
Gas Phase ◽  
Pulse Repetition Frequency ◽  
Repetition Frequency ◽  
Pulse Repetition ◽  
Benzene Oxidation ◽  
Low Temperature Plasma ◽  
Temperature Plasma ◽  
Pulsed Corona

AbstractWastewaters polluted with non-biodegradable volatile organic compounds (VOCs), such as aromatic substances, present a growing problem meeting no adequately affordable technological response. Low-temperature plasma generated in the gas-phase pulsed corona discharge (PCD) presents competitive advanced oxidation technology in abatement of various classes of pollutants, although the process parameters, the pulse repetition frequency and the liquid spray rate, require optimization. The experimental research into aqueous benzene oxidation with PCD was undertaken to establish the impact of the parameters to the energy efficiency. The oxidation reaction was found under the experimental conditions to mostly proceed in the gas phase showing little influence of the pulse repetition frequency and the gas-liquid contact surface. Oxidation of benzene and, presumably, other volatile pollutants in the volume of PCD reactor compartment presents an effective strategy of aqueous VOCs abatement.

Lowtemperature plasma generator for effective processing of materials

2021 ◽  
Vol 77 (5) ◽  
pp. 587-592
Author(s):  
M. Kh. Gadzhiev ◽  
A. S. Tyuftyaev ◽  
Yu. M. Kulikov ◽  
M. A. Sargsyan ◽  
D. I. Yusupov ◽  
...  
Keyword(s):  
Low Temperature ◽  
Flow Rate ◽  
Gas Flow ◽  
Arc Discharge ◽  
Plasma Jet ◽  
Plasma Generator ◽  
Low Temperature Plasma ◽  
Temperature Plasma ◽  
High Enthalpy ◽  
High Resource

Low-temperature plasma is used in metallurgy for steel alloying by nitrogen, deoxidization of magnetic alloys, obtaining of steels with particularly low carbon content, metal cleaning of nonmetallic inclusions, desulfurization and other refining processes. The wide application of those technologies is restrained by absence of reliable generators of low-temperature plasma (GLP) with sufficient resource of continuous operation. As a result of studies, a universal generator of high-enthalpy plasma jet of various working gases was created. The generator has expanding channel of the output electrode with an efficiency of ~60 % for argon working gas and ~80% for nitrogen and air. It was shown that the developed generator of low-temperature plasma ensures formation of a weakly diverging (2α = 12°) plasma jet with a diameter D = 5–12 mm, an enthalpy of 5–50 kJ/g and a mass average temperature of 5–10 kK, at a full electric power of the arc discharge of 5–50 kW and a plasma-forming gas flow rate of 1–3 g/s. Results of the study of propane additions to the plasma-forming gas effect on the state of cathodes with inserts made of pure tungsten, lanthanum tungsten, and hafnium presented. It was shown that a small propane addition (1%) to the plasma-forming gas, results in reducing effect of the insert material. Study of the GLP operation at arc current 100A with addition to the working gas nitrogen maximum possible volume of propane, which don’t disturb stability of arc showed that for the developed plasma generator at the nitrogen flow rate ~0,45 g/s, the propane flow rate was ~0,33 g/s (not more than ~73 % of the plasma-forming gas). The created high-resource GLP with changeable electrodes enables to obtain at the exit a high-enthalpy plasma flow of various gases (argon, nitrogen, air) and can be a prototype of more powerful plasmotrons of various technological application, in particular for plasma metallurgy.

Low temperature silicon epitaxy by photo- and plasma-CVD

1988 ◽  
Author(s):  
A. Yamada ◽  
A. Satoh ◽  
M. Konagai ◽  
K. Takahashi
Keyword(s):  
Low Temperature ◽  
Plasma Cvd ◽  
Silicon Epitaxy

The construction of Mo6−δO3−-supported catalyst for low-temperature propylene gas-phase epoxidation by Cu modification

2018 ◽  
Vol 368 ◽  
pp. 120-133 ◽  
Author(s):  
Zhiyong Wang ◽  
Along Gao ◽  
Peng Chen ◽  
Hui Hu ◽  
Qingming Huang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Gas Phase ◽  
Supported Catalyst

Processing and Characterization of Amorphous Copper Oxide Thin Films Prepared by Reactive Magnetron Sputtering

2018 ◽  
Vol 775 ◽  
pp. 238-245 ◽  
Author(s):  
Thitinai Gaewdang ◽  
Ngamnit Wongcharoen
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Magnetron Sputtering ◽  
Copper Oxide ◽  
Flow Rate ◽  
Localized States ◽  
Positive Sign ◽  
Variable Range Hopping ◽  
Variable Range ◽  
Deposited Films

In this paper, copper oxide (CuOx) thin films with amorphous phase were prepared on glass substrates by reactive dc magnetron sputtering. The influence of the flow rate of O2 on the structural, optical and electrical properties of the as-deposited films was systematically studied. XRD revealed that the as-deposited films remained amorphous in the whole range of adjusted oxygen flow rate. Surface morphology and nanoparticle size of the films were observed by AFM. Electrical resistivity and Hall effect measurements were performed on the films with van der Pauw configuration. The positive sign of the Hall coefficient confirmed the p-type conductivity in all studied films. From temperature-dependent electrical conductivity of the films prepared at R(O2) of 1.5 sccm, it was show that three types of behavior can be expected, nearest-neighbor hopping at high temperature range (200-300 K), the Mott variable range hopping at low temperature (110-190 K) and Efros-Shklovskii variable range hopping at very low temperature (65-100 K). Some important parameters corresponding to Mott-VRH and ES-VRH like density of localized states near the Fermi level, localization length, degree of disorder, hopping distance and hopping energy were determined. These parameters would be helpful for optimizing the performance of photovoltaic applications.

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