| Summary: | 博士 === 國立暨南國際大學 === 電機工程學系 === 95 === Scanning probe lithography (SPL) and E-beam nanolithography (EBL) were adopted in conjunction with anisotropic etching to fabricate a silicon nanowire field-effect transistor (SiNW-FET) and a nanoflash memory on a silicon-on-insulator (SOI) wafer. Also, fabrication of symmetrical (Au/Au) and asymmetrical (Au/poly-Si) nanogap electrode (NGE) arrays by using a sidewall spacer nanofabrication technique was demonstrated. The proposed technique showed that nanogap distances from 10 to 100 nm were easily reproducible on a 6-in wafer.
The properties of different SiNW-FETs with both Schottky contacts and ohmic contacts were discussed with respect to the doping concentration in the semiconductors. Both ambipolar and unipolar transport mechanisms could be achieved in the SiNW-FETs. Applications of SiNW-FETs in nanoelectronics like Schottky-diodes, Schottky-barrier FETs and CMOS inverters are also demonstrated. In order to deal with doping variation on a nanoscale, the effects of surface modifications on the surfaces of SiNWs were studied and were justified to be an effective method for controlling conductivity in the active regions of the SiNW-FETs. In applications of SiNW-FETs to nanobiosensing, intergration of the microfluidic channel (SU8, PDMS) with the SiNW-FET for antibody and steroid detection was demonstrated. When the analytes (steroids and antibodies) were attached to the SiNW surface, the changes in conductance were rerecorded in real time. Detection of the anti-rabbit IgG in a concentration of 10^-12 g/ml and detection of 0.013 fM of 19-NT steroid were also achieved using ultra high sensitive SiNW-FET biosensors.
For applications to nanogap electrodes, the binding of 15-nm gold nanoparticles across 10-nm electrodes, which causes a drastic change in electrical conductance, has also been demonstrated. Under a bias of 3 V, the conductive current increases from 2 pA to 300 nA after the binding of 15-nm gold nanoparticles across the 10-nm electrodes. Using chemical surface modifications, the SiNW-FETs and NGE have broader functionalities in both the electronics and sensing fields.
In order to ensure that the chemical structure after the surface modifications is the same as desired, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectric spectra (XPS) were adopted to analyse the surface chemical states of the sample surface. The morphology and roughness were monitored and justified by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Surface chemical composition was characterized by scanning photoelectron microscopy (SPEM). Further, all the electrical properties are characterized using a precision semiconductor parameter analyzer.
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