Carbonyl mediated attachment to silicon: Acetaldehyde on Si(001)

Abstract

A detailed understanding of the chemical reactions of organic molecules with semiconductor surfaces will greatly aid schemes for the incorporation of organic functionality into existing technologies. In this paper we report on the reaction of acetaldehyde (CH3CHO) with silicon (001) as revealed by a combination of temperature-dependent scanning tunneling microscopy (STM) experiments and density functional theory (DFT). We observe that low-coverage exposures at room temperature result almost exclusively in the formation of a single adsorbate species. Conversion of this structure into thermodynamically favored bridge-bonded structures is achieved through temperature anneals between 150–250 °C. We determine the chemical identity of each of the experimentally observed species by comparison with DFT total energy calculations and simulated STM images. Calculations of transition states are used to formulate a full reaction pathway explaining the formation of the observed species. Excellent agreement is found between our experimental measurements and theoretical calculations. The results also present a picture consistent with our previous work on acetone and reveal a general reaction pattern for molecules containing the acetyl COCH3 functional group, where the initial attachment to the surface is mediated by a carbonyl C=O group. This suggests that modification of the residue R will facilitate in binding other electronically active molecules to the surface in a controlled fashion.

Dissociation of CH3–O as a Driving Force for Methoxyacetophenone Adsorption on Si(001)

“…3,32,39 (see also Table 1). By analogy to acetaldehyde and acetone, 17,34,36 it might also be tempting to assign the 531.4 eV peak to Si−O−C bonding in a strained configuration. However, the additional complexity of the p-methoxyacetophenone molecule may also provide alternative assignments for the two peaks we observe here at low coverage, and we defer definitive assignment of these peaks to the discussion below where we introduce DFT simulation data of O(1s) binding energies for p-methoxyacetophenone adsorbed in different configurations on Si(001).…”

Acetic acid on silicon (001): An exercise in chemical analogy

“…Energies of adsorption and activation energies are calculated using a procedure that we refer to as a cluster compound model, 12,13 which has a solid track record 14,15 of describing processes of molecular dissociation on the Si(001) surface. This approach provides a good estimate of hybrid-DFT (B3LYP; Ref.…”

Atomic-Scale Patterning of Arsenic in Silicon by Scanning Tunneling Microscopy

“…The CCM approach has an established track record of describing the dissociation pathways of small molecules on the Si(001) surface and providing an explanation of the adsorbate species observed in STM experiments (see, e.g. , refs , , , ) The specific approach used here for the AsH 3 /Si­(001) system is exactly the same as in our previous work describing the complex dissociation pathways of the analogous PH 3 /Si­(001) system, and the reader is referred to this article for the full technical details. While this approach may be computationally expensive, it has been proven for the PH 3 system, and its use here allows direct and transparent comparison between the two systems.…”