Temperature-programmed desorption of pyridine on silica overlayers deposited on zirconia and titania by chemical vapor deposition of tetraethoxysilicon (Si(OC2H5)4)

1989 ◽  
Vol 1 (3) ◽  
pp. 308-310 ◽  
Author(s):  
T. Jin ◽  
S. K. Jo ◽  
C. Yoon ◽  
J. M. White
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Temperature Programmed Desorption ◽  
Temperature Programmed

The Reaction of NH3 With TiN: Implications for CVD

1995 ◽  
Vol 410 ◽  
Author(s):  
Michelle T. Schulberg ◽  
Mark D. Allendorf ◽  
Duane A. Outka
Keyword(s):  
Activation Energy ◽  
Chemical Vapor Deposition ◽  
Reaction Temperature ◽  
Vapor Deposition ◽  
High Probability ◽  
Film Growth ◽  
Chemical Vapor ◽  
Temperature Programmed Desorption ◽  
Surface Sites ◽  
Temperature Programmed

ABSTRACTSince NH3 is an important component of TiN chemical vapor deposition (CVD) processes, understanding the NH3/TiN surface interaction is crucial to developing a model for the overall reaction. Temperature programmed desorption experiments show that NH3 adsorbs molecularly on amorphous TiN surfaces. Chemisorption occurs at only ∼5% of the surface sites, with an activation energy for desorption of 24 kcal/mol. The sticking probability into this state is 0.06 at 100 K. In addition, NH3 adsorbs with high probability into a multilayer state with an activation energy for desorption of 7.3 kcal/mol, similar to that found in other systems. NH3 does not dissociate on TiN. Under CVD conditions, however, the reactivity of NH3 on TiN may increase and surface reactions may play a part in film growth.

Catalyst Support and Pretreatment Effects on Carbon Nanotubes Synthesis by Chemical Vapor Deposition of Methane on Iron over SiO2, Al2O3 or MgO

2009 ◽  
Vol 7 (1) ◽  
Author(s):  
M. Esmaieli ◽  
A. Khodadadi ◽  
Y. Mortazavi
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Iron Catalyst ◽  
Supported Catalysts ◽  
Catalyst Support ◽  
Multiwall Carbon Nanotubes ◽  
Chemical Vapor ◽  
Pretreatment Conditions ◽  
Temperature Programmed

In this study we report the effects of support and pretreatment conditions on growth of carbon nanotubes (CNTs) by chemical vapor deposition of methane on iron catalyst supported on MgO, silica or alumina. The iron was impregnated onto the supports, and then the samples were dried, calcined at 550°C and pretreated in either helium or hydrogen up to 1000°C before exposure to methane as a carbon source for CNTs growth. Temperature programmed reduction (TPR) of the fresh catalysts and the ones pre-treated in He and in H2 shows various interactions of the iron with supports at pretreatment conditions. The CNTs are characterized by SEM, Raman, FTIR, and TEM. The IG/ID of Raman spectroscopy are 6.2, 3.8 and 0.7 for the CNTs grown on the MgO, alumina, and silica-supported iron catalysts pretreated in helium, respectively. When the Fe/MgO catalyst is pretreated in hydrogen the IG/ID ratio dramatically reduces to 0.8. A less significant effect of pretreating of the catalysts in hydrogen is observed for silica- and alumina-supported catalysts. RBM peaks of Raman spectra along with TEM results indicate the formation of bundles of 0.8-1.2 nm single-wall as well as multiwall carbon nanotubes on the Fe/MgO catalyst pre-treated in He.

The Interaction of HCl With polycrystalline β-SiC: Evidence for a Site-Blocking Mechanism for HCl Inhibition of SiC CVD

1995 ◽  
Vol 410 ◽  
Author(s):  
Michelle T. Schulberg ◽  
Mark D. Allendorf ◽  
Duane A. Outka
Keyword(s):  
Vapor Deposition ◽  
Electron Spectroscopy ◽  
Chemical Vapor ◽  
Temperature Programmed Desorption ◽  
Etching Mechanism ◽  
Temperature Programmed ◽  
A Site ◽  
Site Blocking ◽  
Blocking Mechanism ◽  
Initial Sticking

ABSTRACTChlorine-containing precursors are attractive for chemical vapor deposition (CVD) of SiC because they are less hazardous and more economical than silane precursors. The reactivity of HCl, a by-product of these reactions, on SiC is of particular interest because it has been reported that HCl inhibits SiC CVD, but the mechanism for this inhibition has not been identified. In this work the adsorption of HCl on polycrystalline β-SiC was examined with Auger Electron Spectroscopy (AES) and Temperature Programmed Desorption (TPD). HCl adsorbs readily on SiC, with an initial sticking probability of 0.1 at 300 K, and forms a strong bond, with an activation energy for desorption of 64 kcal/mol. The only product detected by TPD is HCl, which desorbs in a peak centered at 1010 K. There are no Si- or C-containing desorption products, demonstrating that HCl does not etch SiC under TPD conditions. These results are consistent with a site-blocking mechanism for HCl inhibition of SiC CVD, but not with an etching mechanism.

scholarly journals Catalytic Chemical Vapor Deposition of Methane to Carbon Nanotubes: Copper Promoted Effect of Ni/MgO Catalysts

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Wen Yang ◽  
Yanyan Feng ◽  
Wei Chu
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Calcination Temperature ◽  
Reaction Temperature ◽  
Vapor Deposition ◽  
Sol Gel ◽  
Chemical Vapor ◽  
Growth And Yield ◽  
Calcination Temperatures ◽  
Temperature Programmed

The Ni/MgO and Ni-Cu/MgO catalysts were prepared by sol-gel method and used as the catalysts for synthesis of carbon nanotubes by thermal chemical vapor deposition. The effect of Cu on the carbon yield and structure was investigated, and the effects of calcination temperature and reaction temperature were also investigated. The catalysts and synthesized carbon materials were characterized by temperature programmed reduction (TPR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Results showed that the addition of Cu promoted the reduction of nickel species, subsequently improving the growth and yield of CNTs. Meanwhile, CNTs were synthesized by the Ni/MgO and Ni-Cu/MgO catalysts with various calcination temperatures and reaction temperatures, and results suggested that the obtained CNTs on Ni-Cu/MgO catalyst with the calcination temperature of 500°C and the reaction temperature of 650°C were of the greatest yield and quantity of 927%.

Metallorganic Chemical Vapor Deposition of Ir Films With Iridium Acetylacetonate and Carbonyl Precursors

1998 ◽  
Vol 541 ◽  
Author(s):  
Y.-M. Sun ◽  
J. Endle ◽  
K. Smith ◽  
J. G. Ekerdt ◽  
R. L. Hance ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Gas Phase ◽  
Vapor Deposition ◽  
Film Growth ◽  
Chemical Vapor ◽  
Film Deposition ◽  
Film Deposition Rate ◽  
Phase Nucleation ◽  
Temperature Programmed ◽  
Reactive Gas

AbstractIridium acetylacetonate, dicarbonylacetylacetonato iridium, and tetrakisiridium dodecacarbonyl (iridium carbonyl) have been evaluated for metallorganic chemical vapor deposition (CVD) of pure iridium films. Temperature programmed mass spectroscopy reveals that iridium tris-acetylacetonate and dicarbonylacetylactonato iridium have high thermal stability and sublime at 200 and 100 °C in vacuum, respectively. Iridium carbonyl decomposes upon sublimation at temperatures above 120 °C. Pure CVD Ir films were obtained using iridium carbonyl; however, carbon is incorporated into the iridium films with the iridium trisacetylacetonate and dicarbonylacetylactonato iridium precursors unless a reactive gas, such as oxygen is co-dosed. Co-dosed oxygen also increases the film deposition rate and significantly decreases the film growth temperatures. Particles were found on the films grown with iridium carbonyl between 280 to 400 °C, indicating that gas phase nucleation occurred during deposition.

Surface Chemistry of Fluorine-Containing Molecules Related to CVD Process on Silicon Nitride: SiF4, XeF2, and HF

1991 ◽  
Vol 250 ◽  
Author(s):  
Duane A. Outka
Keyword(s):  
Silicon Nitride ◽  
Vapor Deposition ◽  
Electron Spectroscopy ◽  
Polycrystalline Silicon ◽  
Auger Electron ◽  
Chemical Vapor ◽  
Temperature Programmed Desorption ◽  
Auger Peak ◽  
Rate Determining Step ◽  
Temperature Programmed

AbstractThe reactivity of several fluorine-containing molecules on a polycrystalline silicon nitride (Si3N4) surface is studied under ultrahigh vacuum (UHV) conditions using temperature programmed desorption (TPD) and Auger electron spectroscopy (AES). The chemistry of fluorine on Si3N4 is of interest in understanding the high temperature chemical vapor deposition (CVD) of Si3N4, which uses SiF4 as a starting material. XeF2 is reacted with a Si3N4 surface to prepare and characterize various surface SiFx (1 ≤ × ≤ 3) species. These are identified by the chemical shift induced by the fluorine atoms in the Si (LMM) Auger peak and by changes in the TPD. Of these species, SiF2 is stable to the highest temperature. SiF2 is also formed by the reaction of SiF4 with a Si3N4. Because SiF2 is so stable, its decomposition is proposed as a rate-determining step in the CVD deposition of Si3N4 from SiF4. Gaseous HF, which is a product of the CVD process, does not dissociate on Si3N4 and is therefore unlikely to cause the etch-like marks on the Si3N4 coating that are observed under certain conditions.

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