| Summary: | 碩士 === 國立臺北科技大學 === 有機高分子研究所 === 97 === Advances in nanofabrication technology have made lithographically made silicon-nanowire field-effect-transistors an emerging charge sensor. To enable the sensor function for chemical species, the surface of the nanowires has to be attached with a hetero-interface which serves as a linker to the target molecules. In this thesis work, surface modification of hetero-interface molecules on silicon nanowires made on Silicon-On-Insulator wafers is studied. Specifically, APTES (3-Aminopropyltriethoxysilane) was employed as the interface molecule whose structure ordering was shown to be improved by an externally applied parallel electric field, and the degree of ordering was probed by the underneath silicon nanowires field-effect-transistors. For instance, we showed that an upward electric field can align the APTES molecules on the surface of p-type silicon nanowires.
The alignment, causes an increased global dipole-polarization and produces positive effective charges. Consequently, the hole-carriers in the nanowires are repelled, resulting in a decreased source-drain current. Contrarily, a downward electric field would suppress the molecular dipole charge, yielding a current increase. As an independent clew, the effect of field-induced structure ordering was confirmed by angle-resolved X-ray photoelectron spectroscopy studies. Ordering of the interface linker molecules is important for field-effect-based sensors, and the effect we demonstrated in this thesis provides a simple, yet reliable way for improved sensitivity.
|
|---|
