| Summary: | 博士 === 臺灣大學 === 材料科學與工程學研究所 === 98 === One-dimensional (1D) nanowires fabricated from different materials are potential candidates for the next generation of electronic devices. On the one hand, devices based on 1D nanowires exhibit fascinating transport phenomena which can be described in the context of mesoscopic physics rather than the well-known Ohm’s law. On the other hand, 1D semiconductor wires are ideal charge sensors due to their relatively large surface area. In this thesis, electron transport properties in 1D InN nanowires and sensor application using Si-nanowires are investigated.
Owing to the large surface-to-volume ratio, the transport characteristics of InN nanowires are generally governed by the surface charges. Because of relatively low density, the electron-electron interaction is noticeable. The motion of these surface charges can be described by mesoscopic physics in which, electron wave nature is notable and long-range electron correlation cannot be overlooked. In the 1D nanowire devices that we studied, the low temperature transport behaviors were depending on the lead-wire contacts and the wire defects. For devices with low contact resistances, the wires exhibited magnetoresistance fluctuations associated with weak disorder system, and for devices with high contact resistances, Coulomb blockade behaviors due to strong localization of electrons in the wires were generally observed. Furthermore, we also found superconductivity in an individual InN nanowire.
When the 1D nanowire is fabricated into a sensor, its surface is modified with an active target molecular layer, and the variation in the molecular charge is reflected by a change in the wire conductance. In our study, silicon nanowires are employed to characterize the polarization of surface molecules and to detect the hybridization between complimentary single-stranded DNA molecules. Furthermore, we showed it is possible to order the surface molecules by an external electric field, and the degree of ordering can be detected by the underneath nanowire.
1D nanowire is an interesting subject to investigate not only because of its rich transport phenomena that provide a good playground for studying mesoscopic physics, but also the high-sensitivity that allows detection of reactions at molecular levels. With its high charge-sensitivity, the incorporation of 1D nanowire with current CMOS electronic devices may results in an innovative era for future semiconductor electronics.
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