Methylamine Adsorption on and Desorption from Si(100)

Abstract

The adsorption of several simple methylamines on the Si(100)-(2 × 1) surface has been investigated using Auger electron spectroscopy (AES), thermal desorption spectroscopy (TDS), low-energy electron diffraction, and computational modeling. Both methylamine and dimethylamine appear to undergo mostly dissociative adsorption on this surface at room temperature, although trapping into a molecular adsorption well appears to occur to a limited extent for both molecules. Trimethylamine appears to undergo mostly molecular adsorption on this surface. These results are in agreement with recent computational, infrared, and photoemission spectroscopic studies of these systems. By comparison to the AES results from the adsorption of methyl iodide on Si(100), it was concluded that the surface saturation coverage of trimethylamine on Si(100) is 0.26 monolayers, consistent with the photoemission results, while both methylamine and dimethylamine appear to saturate at about 0.48 monolayers. TDS reveals parent desorption channels for all three of these molecules, as well as competing surface decomposition channels. The adsorption energies obtained from computational treatments of these systems are consistent with the experimentally derived values.

Adsorption and Decomposition Pathways of Cyanogen Halides on Si(100)−(2×1)

“…26 Similar results are also found for methylamine adsorption on Si single-dimer clusters. 4,24 Thus, all further calculation are performed at the B3LYP/6-31G(d) level.…”

“…For molecular ammonia adsorption, a 25 kJ/mol difference is found between a single dimer and larger clusters using B3LYP/6-31G-(d), 26 while a 28 kJ/mol difference is found using B3LYP/6-311+G(2d,p). 24 This energy difference is attributed to a greater ability of the larger clusters to delocalize the additional density created by the dative bond along the dimer row. 26 For the analogous HCN configuration, Bacalzo-Gladden et al find an energy difference, including zero-point corrections, of 28 kJ/ mol between the single-and double-dimer silicon clusters.…”

Electron‐beam‐induced decomposition of trimethylamine on Si(100)‐2 × 1

“…7 Figures 1 and 2 show two TPD runs for a dose of 0.2 L of TMA on Si(100)-2 ð 1 at 102 K. Large desorption peaks are seen at low temperature, which correspond to desorption of the intact TMA from a physisorbed layer on the surface. At higher temperatures, as seen in Fig.…”

Adsorption dynamics of tetrahydrofuran on Si(0 0 1) studied by means of molecular beam techniques

“…From low-temperature STM experiments, ε a = 0.13 eV was deduced for ethylene/Si(0 0 1) [9]; thus the binding energy of the -complex intermediate of ethylene on silicon is ε d = 0.33 eV. Experimental values for the binding energy of datively bonded systems on Si(0 0 1) are available for tertiary amines, e.g., 1.1 eV was reported in the case of trimethyl amine on Si(0 0 1) [30]. Although one expects a somewhat lower binding energy for the dative bond of oxygen on Si(0 0 1) due to its higher electronegativity, a conversion barrier significantly higher than 0.1 eV, i.e., the value for ethylene/Si(0 0 1), can be deduced from our experiments for THF/Si(0 0 1).…”