Electrical characterization of a phenylacetylene-modified silicon surface via mercury probe

Abstract

The influence of phenylacetylene molecules on a silicon (100) surface has been investigated by formation of metal–molecule–semiconductor junctions with soft mercury contacts. Molecules are bonded covalently to the semiconductor surface via Si–C bonds by thermochemical reaction. The chemical bonding of these molecules is confirmed by XPS measurements. Current–voltage and capacitance–voltage curves were recorded under dark and light on these junctions to understand the role of the organic molecules. Junctions with phenylacetylene molecules are more ideal, with an extra density of surface states which are responsible for quenching photoconductivity. The presence of surface states is reflected as well-defined peaks in low frequency photocapacitance curves.