Adsorption and Decomposition of Trimethylarsenic on GaAs(100)

1988 ◽  
Vol 131 ◽  
Author(s):  
J. R. Creighton
Keyword(s):  
Activation Energy ◽  
Electron Irradiation ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Temperature Programmed Desorption ◽  
Methyl Radicals ◽  
Arsenic Compounds ◽  
Group V ◽  
Desorption Activation Energy ◽  
Temperature Programmed

ABSTRACTAlkylated arsenic compounds have shown some promise as alternatives to arsine as the group-V source gas for GaAs MOCVD. However, little is known about the fundamental chemical interactions of these compounds with the GaAs surface. We have investigated the adsorption and reactivity of trimethylarsenic (TMAs) on GaAs(100) using temperature programmed desorption (TPD), Auger electron spectroscopy, and LEED. For the exposures and temperatures studied, TMAs did not pyrolytically decompose on the GaAs(100). TPD results indicate that TMAs chemisorbs, apparently non-dissociatively, and desorbs ≅330 K. Multilayers of TMAs desorb ≅140–160 K. Exposure of adsorbed TMAs to 70 eV electrons results in irreversible decomposition of the molecule. After electron irradiation, TPD shows that methyl radicals desorb at 660 K, which corresponds to a desorption activation energy of ≅40 kcal/mol. At higher temperatures, As2, H2, C2H2, and a smaller amount of methyl radicals desorb, and a small coverage of carbon remains on the surface.

Adsorption and Desorption Kinetics for Chlorosilanes on Si(111) 7×7

1990 ◽  
Vol 204 ◽  
Author(s):  
P. Gupta ◽  
P.A. Coon ◽  
B.G. Koehler ◽  
M.L. Wise ◽  
S.M. George
Keyword(s):  
Activation Energy ◽  
Surface Coverage ◽  
Temperature Programmed Desorption ◽  
Desorption Kinetics ◽  
Sticking Coefficient ◽  
Temperature Dependent ◽  
Adsorption And Desorption ◽  
Desorption Activation Energy ◽  
Temperature Programmed ◽  
Sticking Coefficients

ABSTRACTThe adsorption and desorption kinetics for SiCl4 and SiCl2H2 on Si(111) 7×7 were studied using laser-induced thermal desorption (LITD) and temperature programmed desorption (TPD) techniques. Both LITD and TPD experiments monitored SiCl2 as the main desorption product at 950 K at all coverages of SiCl4 and SiCl2H2 on Si(111) 7×7.HC1 desorption at 850 K and H2 desorption at 810 K were also observed following SiCl2H2 adsorption. Isothermal LITD measurements of SiCl4 and SiCl2H2) adsorption on Si(111) 7×7 revealed that the initial reactive sticking coefficient decreased with increasing surface temperature for both molecules. The temperature-dependent sticking coefficients were consistent with precursor-mediated adsorption kinetics. Isothermal LITD studies of SiC12 desorption revealed second-order SiCl2 desorption kinetics. The desorption kinetics were characterizedby a desorption activation energy of Ed = 67 kcal/mol and a preexponential of vd = 3.2 cm2/s. TPD studies observed that the HCI desorption yield decreased relative to H2 and SiCl2 desorption as a function of surface coverage following SiCl2H2 exposure. These results indicate that when more hydrogen desorbs as H2 at higher coverages, The remaining chlorine is forced to desorb as SiCl 2.

Adsorption of Styrene on Hydrochloric Acid-Modified Sepiolite

2012 ◽  
Vol 518-523 ◽  
pp. 2058-2063
Author(s):  
Zhao Du ◽  
Bin Bin Yang ◽  
Er Hong Duan ◽  
Bin Guo
Keyword(s):  
Activation Energy ◽  
Hydrochloric Acid ◽  
Surface Area ◽  
Temperature Programmed Desorption ◽  
Micropore Volume ◽  
Breakthrough Curves ◽  
Adsorption Capacities ◽  
Desorption Activation Energy ◽  
Temperature Programmed ◽  
Fixed Beds

In this work, the breakthrough curves of styrene in fixed beds packed separately with hydrochloric acid-modified sepiolite were determined. And the Temperature Programmed Desorption (TPD) method is applied to research the desorption activation energy on modified sepiolite and untreated sepiolite. The results showed that in compared with the original sepiolite, the hydrochloric acid-modified sepiolite had more surface basic groups, pore volume and higher surface area so that their adsorption capacities of styrene were improved. The sepiolite modified with 12% hydrochloric acid solution had more micropore volume and higher surface area than the other modified sepiolite, and thus its adsorption capacity of styrene was the highest. The activation energy for desorption of styrene on the modified is higher than on the original sepiolite, this show that using hydrochloric acid modified sepiolite can enhance its adsorption of styrene.

The Reactivity of HCI and Methyltrichlorosilane with Silicon Carbide Surfaces

1992 ◽  
Vol 282 ◽  
Author(s):  
Mark D. Allendorf ◽  
Duane A. Outka
Keyword(s):  
Silicon Carbide ◽  
Auger Electron Spectroscopy ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Temperature Programmed Desorption ◽  
Stable Surface ◽  
Temperature Programmed

ABSTRACTThis work explores the reactivity of HCI and methyltrichlorosilane (MTS) with polycrystalline β-silicon carbide (SiC) surfaces using temperature-programmed desorption (TPD) and Auger electron spectroscopy. HCl is a corrosive gas that inhibits SiC deposition. The results show that HCl is adsorbed by SiC, forming a stable surface chloride that could inhibit SiC deposition. TPD shows that chlorine desorbs as HCI or SiCl4, confirming that HCl can etch SiC surfaces. Desorption is rate-limited by the breaking of Si-Cl bonds. MTS is also adsorbed by SiC; its desorption is similar to that of HCI.

Adsorption and Reaction of TiCl4 on W(100)

1993 ◽  
Vol 334 ◽  
Author(s):  
Wei Chen ◽  
Jeffrey T. Roberts
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Titanium Tetrachloride ◽  
Bound State ◽  
Temperature Programmed Desorption ◽  
X Ray ◽  
Low Energy Electron Diffraction ◽  
Low Energy Electron ◽  
Temperature Programmed

AbstractThe adsorption and reaction of titanium tetrachloride (TiC14) on W(100) was investigated using temperature programmed desorption mass spectrometry (TPRS), x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and low energy electron diffraction (LEED). TiC14 adsorbs molecularly on W(100) at 100 K. Desorption from the molecularly bound state occurs near 220 K. Competing with desorption is dissociation to adsorbed TiCl3, which reacts to form gaseous TiCl4 near 450 K. TiC13 also decomposes into atomically adsorbed Ti and Cl on the surface upon heating to 700 K.

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.

Surface Chemistry of Dimethylaluminum Hydride and Trimethylaluminum on Aluminum

1989 ◽  
Vol 158 ◽  
Author(s):  
Daniel R. Strongin ◽  
Paul B. Comita
Keyword(s):  
Surface Chemistry ◽  
Auger Electron Spectroscopy ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Temperature Programmed Desorption ◽  
Aluminum Surface ◽  
Desorption Peak ◽  
Carbonaceous Species ◽  
Temperature Programmed ◽  
Dimethylaluminum Hydride

ABSTRACTThe surface chemistry of dimethylaluminum hydride (DMAH) and trimethylaluminum (TMA) on aluminum has been investigated with temperature programmed desorption (TPD), and Auger electron spectroscopy (AES). The TPD spectra of TMA shows a single desorption peak with a peak maximum which shifts from 190 to 200 K for surface coverages of 0.5 and 2.0 monolayers (ML) respectively. DMAH desorbs from an aluminum surface between 198 and 236 K at surface coverages ranging from 0.1 to 4.0 ML. A second DMAH desorption peak is observed at about 200 K (2.0 ML) when the aluminum surface is contaminated with carbonaceous species, resulting from the decomposition of DMAH. Both DMAH and TMA yield methane as a reaction product on the aluminum surface. The surface reactions of DMAH on aluminum also yield TMA as a reaction product.

Influence of the terminal group on the thermal decomposition reactions of carboxylic acids on copper: nature of the carbonaceous film

2021 ◽  
Author(s):  
Robert Bavisotto ◽  
Resham Rana ◽  
Nicholas Hopper ◽  
Kaiming Hou ◽  
Wilfred T. Tysoe
Keyword(s):  
Thermal Decomposition ◽  
Carboxylic Acids ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Temperature Programmed Desorption ◽  
Terminal Group ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Decomposition Reactions ◽  
Temperature Programmed

The effect of the terminal groups on the nature of the films formed by the thermal decomposition of carboxylic acids on copper is studied in ultrahigh vacuum using temperature-programmed desorption (TPD), scanning tunneling microscopy (STM) and Auger electron spectroscopy (AES).

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