open access

https://hdl.handle.net/2115/50226

Electron Transfer through Organic Monolayers Directly Bonded to Silicon Probed by Current Sensing Atomic Force Microscopy : Effect of Chain Length and Applied Force

英語

2004-11-04

American Chemical Society

Journal of Physical Chemistry B

108(44)

17129-17135

Electron transfer through organic monolayers directly bonded to a silicon surface has been investigated by using a current sensing atomic force microscope (CSAFM). The research system employs a platinum-coated CSAFM tip in point contact at a confined nanometer size with a set of alkyl monolayers of various chain lengths, which are covalently bonded directly to an n-type Si(111) by immersing a H-terminated silicon substrate in neat CH2=CH-(CH2)_[n-3]CH3 (n = 12, 14, 16, and 18) under heating. The current flows were analyzed with a modified electron-tunneling model and showed strong force and chain length dependences. Increasing the applied force resulted in a negative shift of the current-voltage (I-V) curves. This observation was mainly explained by the amplified contact area and shortened tunneling distance. In addition, the I-V curves showed chain length dependence, from which the bias-dependent electron tunneling coefficient, β, was analyzed.

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