Highly Stable Organic Modification of Si(111) Surfaces: Towards Reacting Si with Further Functionalities while Preserving the Desirable Chemical Properties of Full Si-C Atop Site Terminations

摘要

Densely packed organic layers bonded covalently to crystalline silicon (Si) surfaces, without an interfacial silicon oxide (SiO_2 layer, have received an increasing interest, mainly because of their variety of applications in micro- and nanoelectronics as well as in (biochemical sensors. For example, attachment of organic species on a Si substrate could significantly reduce the density of trap states on Si surfaces as well as the diffusion of oxygen into Si during formation of insulating or high-dielectrics layers. To this end, formation of Si-C bonds is particularly attractive owing to their kinetic inertness as compared to Si-O or Si-H bonds. Si-C bonds are chemically more stable than Si-O bonds, because they are less polarized and thus less susceptible to nucleophilic substitution reactions. Complete coverage of Si atop sites was achieved by CH_3 termination of Si(l 11), through the two-step chlorination/alkylation process. Though CH_3 termination gives full coverage, further functionalization (by reaction with other molecules) is not possible.