期刊
ACS NANO
卷 5, 期 7, 页码 5620-5626出版社
AMER CHEMICAL SOC
DOI: 10.1021/nn201184c
关键词
silicon; nanowire; transistor; sensor; volatile organic compound; nonpolar
类别
资金
- European Commission
- U.S.-Israel Binational Science Foundation
Silicon nanowire field effect transistors (Si NW FETs) are emerging as powerful sensors for direct detection of biological and chemical species. However, the low sensitivity of the Si NW FET sensors toward nonpolar volatile organic compounds (VOCs) Is problematic for many applications. In this study, we show that modifying Si NW FETs with a silane monolayer having a low fraction of S1-O-Si bonds between the adjacent molecules greatly enhances the sensitivity toward nonpoiar VOCs. This can be explained in terms of an indirect sensor -VOC interaction, whereby the nonpolar VOC molecules induce conformational changes in the organic monoiayer, affecting (i) the dielectric constant and/or effective dipole moment of the organic monolayer and/or (ii) the density of charged surface states at the SiO(2)/monolayer interface. In contrast, polar VOCs are sensed directly via VOC-induced changes in the Si NW charge carriers, most probably due to electrostatic interaction between the Si NW and polar VOCs. A semiempirical model for the VOC-induced conductivity changes in the Si NW FETs is presented and discussed.
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