Properties of electronic traps at silicon/1-octadecene interfaces

Silicon surfaces with (111) orientation were hydrogenated in NH4F solution. Alkyl chain monolayers were self-assembled on the hydrogen-terminated sili con (Si-H) surface by the free-radical reaction of 1-octadecene and SiH, ac tivated by ultraviolet (253.7 nm) illumination. Comprehensive electrical ch aracterization of the metal/1-octadecene/silicon structures yielded experim ental data on the (silicon-monolayer) interface trap parameters. The admitt ance data indicated the realization of a true silicon/organic-monolayer int erface. The interface trap density obtained, for p-type silicon, was 1.7-3. 0 x 10(11)/cm(2) V over an energy range of 0.22-0.73 eV over the valence ba nd edge. These interface trap densities can be considered remarkably low fo r a silicon interface formed around room temperature, and are an order of m agnitude lower than what was obtained in the case of alkyl chain organic mo nolayers on naturally oxidized silicon surfaces. The interface trap density was found to be strongly influenced by the silicon doping type and density . This observation suggests that the position of the surface Fermi level ha s a strong influence on the quality of the octadecene-silicon interface. (C ) 2001 American Institute of Physics.