Atomic force microscope anodization of Si(111) covered with alkyl monolayers

Alkyl monolayers on Si were prepared through the reaction between 1-alkenes and hydrogen-terminated Si by heat treatment. The monolayers were characterized by atomic force microscopy (AFM), force curve and water contact angle measurements. It was found that surface properties were modified by the formation of highly ordered closely packed monolayers. The monolayers were anodized with a contact-mode AFM by applying voltage between the conductive cantilever and surface under ambient conditions, which resulted in nanometer-scale oxidation of surfaces. After anodization, patterned areas were modified by removing the silicon oxide and terminating the surface of the grooves with hydrogen atoms by NH4F etching, and by covering the etched surface with 1-octadecene molecules. The monolayers themselves showed high resistance to NH4F etching and air oxidation. AFM lithography of monolayers anchored covalently on Si was found to be useful for nanofabrication of organic/inorganic interfaces based on Si-C covalent bonds.