Surface Reactions of 1-Propanethiol on GaAs(100)

Abstract

The adsorption and decomposition pathways of 1-propanethiol on a Ga-rich GaAs(100) surface have been investigated using the techniques of temperature programmed desorption, X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (TOF-SIMS). 1-Propanethiol adsorbs dissociatively on a clean GaAs(100) surface to form propanethiolate and hydrogen. Further reactions of these species to form new products compete with the recombinative desorption of molecular propanethiol. The C-S bond scission in the propanethiolate results in the formation of propyl species and elemental sulfur. The generation of propene via beta-hydride elimination then follows. In addition, propane and hydrogen form via reductive elimination processes. A recombinative high-temperature propanethiol desorption state is also observed. XPS and TOF-SIMS analyses confirm the presence of sulfur on the GaAs(100) surface following thermal decomposition. This paper discusses the mechanisms by which these products form on the GaAs(100) surface.

Adsorption Kinetics of Hydrogen Sulfide and Thiols on GaAs (001) Surfaces in a Vacuum

“…Available XPS data for liquid deposition of thiol SAMs on GaAs are controversial, with reports of As-S bonding 10,13 or, by contrast, unresolved Ga-S or As-S bonding. 8,12 It should be noted that observed shifts in As binding energies could be partially caused by the presence of As-H bonds, as we have shown that hydrogen desorption is a very unfavorable process, at least on surfaces prepared in a vacuum.…”

“…The absence of this peak in the spectra following thiol deposition is expected since the amount of SH species on the surface in this case is much smaller than after H 2 S decomposition. 8,9 Thus, only direct surface hydrogen recombination is possible after thiol deposition, while after H 2 S adsorption, this process is less efficient and only contributes to the observed broadening of the peak at 480 K.…”

“…6 Thiol deposition on GaAs surfaces is possible from both vapor [7][8][9] and liquid [10][11][12][13][14] phases. However, SAM formation was investigated only for liquid-phase deposition.…”

Adsorption and thermal reaction of short-chain alkanethiols on GaAs(100)

“…To understand the chemical behavior of alkanethiolate SAMs with long alkyl chains, the reaction mechanisms of small alkanethiols have been investigated on GaAs [19,20]. These small alkanethiols represent suitable analogues.…”

Plasmachemical Double Click Thiol–ene Reactions for Wet Electrical Barrier

“…The low level of oxygen can be attributed to some aerial surface oxidation during sample transfer from the plasma deposition chamber. 35,36 The C(1s) spectra were consistent with hydrocarbon (285.0 eV) and carbon-sulfur (286.9 eV) environments, Supporting Information Figure S The infrared spectrum of allyl mercaptan precursor displays a strong allyl CH 2 stretch absorbance (3080 cm -1 ), 40 which disappears upon plasma deposition, Figure 6. As expected, this feature was absent for both 1-propanethiol monomer and its corresponding plasma polymer.…”