Adsorption and Reaction of C₂N₂ on Si(100)-2 × 1:  A Computational Study with Single- and Double-Dimer Cluster Models

Abstract

The adsorption and decomposition of C 2 N 2 on the Si(100)-2 × 1 surface have been calculated by the hybrid density functional B3LYP method with Si 9 H 12 and Si 15 H 16 as single-and double-dimer models, respectively. The result of our single-dimer surface model calculation shows that the surface reaction started from a single N atom of C 2 N 2 molecularly adsorbed on one silicon atom of the dimer. From the result of bond distance changes and vibrational frequency analysis, this process occurs by direct interaction of the CtN group with a silicon dangling bond. Two different reaction paths follow; the first path occurs by the adjoined carbon atom adsorption producing four-member-ring product -Si-N-C-(CN)Si-, similar to the HCN molecule adsorbing sideway on this surface. The other path occurs by the adsorption of the second nitrogen atom with another Si atom producing a six-member-ring product, -Si-N-C-C-N-Si-. The mechanisms for the decomposition of these adsorbates have been elucidated. The result of our calculation with the double-dimer surface model reveals that the reaction barriers are somewhat lower than single-dimer system for either CC or CN bond-breaking processes but with a similar trend. The predicted stabilities of various surface species from physisorbed C 2 N 2 to chemisorbed CN radicals and silicon nitride and silicon carbide are consistent with the results of our previous studies using HREELS, XPS, UPS, and TPD methods as well as with others' data for similar reactions of CN-containing species with the Si(100)-2 × 1 surface. The predicted result for adsorption of two C 2 N 2 based on both surface models indicates a significant decrease in the adsorption energy for the second C 2 N 2 molecule.

Atomistic Insight into Nitrogen-Terminated Diamond(001) Surfaces by the Adsorption of N, NH, and NH2: A Density Functional Theory Study

“…In these prior reports, the assignment was made in reference of systems of remote relevance, that is, NH 3 :CH 3 COOD multilayers, 50 NH 3 :CO 2 multilayers, 51 and C 2 N 2 /Si(001). 52 In light of the current work, CN stretch can be ruled out, and the feature at 197 meV represents solely the N−H bend mode for NH 2 (ad).…”

“…It is noted that our results are in discrepancy with the prior HREELS work, − in which the feature at 197 meV was assigned to the CN stretch and/or N–H bend. In these prior reports, the assignment was made in reference of systems of remote relevance, that is, NH 3 :CH 3 COOD multilayers, NH 3 :CO 2 multilayers, and C 2 N 2 /Si­(001) . In light of the current work, CN stretch can be ruled out, and the feature at 197 meV represents solely the N–H bend mode for NH 2 (ad).…”

Nitrogen-Terminated Polycrystalline Diamond Surfaces by Microwave Chemical Vapor Deposition: Thermal Stability, Chemical States, and Electronic Structure

“…The component centered at ∼180 meV is attributed to C=C stretching vibrations related to graphitic carbon present at the grain boundaries. The peak at ∼200 meV is attributed to N–H bending and C=N stretching modes. ,, Its intensity decreased upon annealing, which indicates that the nitrogen desorbs from the N-diamond surface. Similarly, four components centered at ∼348, ∼364, ∼383, and ∼402 meV are considered for deconvolution of the ∼360 meV peak.…”

Incorporation of nitrogen into polycrystalline diamond surfaces by RF plasma nitridation process at different temperatures: Bonding configuration and thermal stabilty studies by in situ XPS and HREELS

“…a, viz . : (i) appearance of a broad peak centered at ∼176 meV with a distinguished shoulder at 197 meV, which is associated to NH bending and CN stretching modes ; (ii) absence of the optical phonon overtone of diamond at ∼305 meV; (iii) appearance of a well‐defined peak at 426 meV, associated to NH stretching mode . The corresponding HREEL spectrum (Fig.…”