Electrochemical impedance and solid-state electrical characterization of silicon (1 1 1) modified with ω-functionalized alkyl monolayers

In order to reveal the relationship between the dipole moment and electric properties of organically modified semiconductor, a series of ω-functionalized alkyl monolayers on oxide-free silicon (Si–(CH2)10COOH, Si–(CH2)11CH3, Si–(CH2)10COOC2H5, and Si–(CH2)11OH) was prepared and characterized. Electrochemical impedance measurements showed excellent insulating effects of these monolayers. It has been demonstrated that the dielectric constants of these organic monolayers are affected by the dipole moments introduced by the different terminal-groups. Solid-state electrical measurements showed that mercury | ω-functionalized alkyl monolayer | silicon junctions exhibit molecular tunability and a clear correlation between ideality factor and the film thickness/dielectric constant ratio. The barrier height is approximately proportional to the dipole moment of the monolayer. These results augment the possibility of fine-tuning the electrical properties of silicon-based microelectronic devices using functionalized organic monolayers.