Second-harmonic generation from chemically modified Ge(111) interfaces

Abstract

Surfaces of chemically modified germanium were investigated by second harmonic generation (SHG). Wet chemical covalent binding of decyl and sulfur directly to the germanium interface was used to achieve chemical modification. The effects of chemical modification were discussed in terms of polarization variation of the surface bonds and surface backbonds along with surface strain effects. The surface contribution to SHG was found to be diminished for less electronegative species bound to the surface. It was also found that the relative contribution of surface versus bulk to SHG was different for different combinations of polarization and the surface contribution to the p-in/p-out response was the greatest.