Photoconductivity and spin-dependent photoconductivity of hydrosilylated (111) silicon surfaces

Organic monolayers were prepared on hydrogen-terminated (111) silicon surfaces by thermally induced hydrosilylation with alkenes. The electronic properties of the modified surfaces were studied by photoconductivity and spin-dependent photoconductivity measurements (electrically detected magnetic resonance) and compared to the oxidized and hydrogen-terminated silicon surfaces. The photoconductivity at low intensity of illumination (monomolecular recombination regime) indicates that the hydrosilylated surface has nearly as few defects as the surfaces treated in HF vapor. The paramagnetic defects detected in the spin-dependent photoconductivity are identified as the silicon dangling bond Pb-center. The density of defects at the hydrosilylated (111) silicon surface is determined by electron spin resonance measurements to be about 1013 cm−2.