Aminoxyl Radicals on the Silicon (001) Surface

Abstract

Aminoxyl radicals form a class of persistent radical species of which the TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) molecule is perhaps the best known. They are known to be dangling bond scavengers and bind readily to the silicon (001) surface. However, the possibility of the aminoxyl group reacting dissociatively with the surface has been largely ignored. Density functional theory is used to investigate possible reaction pathways for the simplest aminoxyl radical, H2NO, on silicon. We consider same-site, same-dimer, and adjacent-dimer dissociation pathways and find that H2NO dissociates readily in the presence of neighboring free dimers or dangling bonds. Further calculations examine the applicability of these findings to the larger dimethyl aminoxyl and TEMPO molecules.