Wet-Process Molecular Planting in A Specific Site on Silicon with Si-C Covalent Bonds

Abstract

ABSTRACTAlkyl monolayers anchored covalently on silicon were prepared through the reaction between 1-alkenes and hydrogen-terminated silicon (111) surfaces. The 2D-patterning of the surface was done by local oxidation with an atomic force microscope (AFM) and 3D-molecular assemblies were fabricated by immobilization of molecules in a specific site of the patterned surface. The surfaces were anodized with a contact-mode AFM by applying a positive bias voltage to the surface with respect to the platinum-coated cantilever under ambient conditions, which resulted in nanometer-scale oxidation of surfaces. The anodized areas were etched and terminated with hydrogen atoms by NH4F solution, in which we could immobilize various molecules having C=C bonds. We put arylamine molecules to which organic dyes such as fluoroscein were anchored. The intensity of luminescence varied depending on dopant concentration of substrates. Luminescence was very weak on highly-doped silicon possibly due to effective energy transfer from dyes to substrates. The method demonstrated is one of the promising ways to fabricate 3D-assemblies of molecular-scale electronic devices with a stable interface on silicon.