Stability of small chemical groups on hexagonal-SiC(0001) surfaces: A theoretical study

• Published in: Surface science Vol. 606; no. 15-16; pp. 1195 - 1202
• Main Authors: Spillebout, F., Stauffer, L., Sonnet, Ph, Mayne, A.J.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01.08.2012; Elsevier
• Subjects: Adsorption; Chemical bonds; Chemical Sciences; Complex systems; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Density functional theory; DFT calculations; Diimide; Exact sciences and technology; Material chemistry; Mathematical analysis; Physics; Silicon carbide surfaces; Stability; Surface chemistry; Surface properties; Surface properties; Adsorption; Silicon carbide surfaces; DFT calculations; Silicon carbide; Inorganic compounds; Theoretical study; Density functional method
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2012.03.022

Density functional theory (DFT) calculations are used to investigate the stability on SiC(0001) surfaces of different chemical groups -NH2, -NO2, -CH3, -OH, -SH and -CN. The adsorption stability decreases in the order -NO2>−OH>−NH2>−SH>−CN>−CH3. The stability of the single molecule-substrate bond is strongly influenced by the polarizability, which in turn depends on different parameters such as the electronegativity, atomic size and chemical environment. In a further step, methyl (−ACH3) and phenyl (−AC6H5) substituted groups are also considered and similar behaviour is observed. The inductive effect of the -CH3 or -C6H5 groups modifies the polarization of the Si adatom-molecule bond and the steric hindrance due to their size influences the molecular orientation. These two parameters affect the calculated adsorption energy, and are more important for –C6H5 substituent. This study provides clear tendencies that can be applied to more complex systems. Comparison of the adsorption of two large molecules, H2Pc (metal-free phthalocyanine) and PTCDI (perylene tetracarboxylic diimide) on the SiC(0001) surface is presented as an example. ► Investigate the stability on SiC(0001) surfaces of different chemical groups -NH2, -NO2, -CH3, -OH, -SH and –CN. ► Influence of the electronegativity, atomic size and chemical environment. ► Methyl (−ACH3) and phenyl (−AC6H5) substituted groups are also considered. ► Study provides clear tendencies that can be applied to more complex systems.