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Preparation of the Silicon Nanowires Array and Its Application in Chemical and Biological Sensors

Author: WanLiJuan
Tutor: ZhangJian
School: East China Normal University
Course: Microelectronics and Solid State Electronics
Keywords: silicon nanowires (SiNWs) mechanism metal-insulater-semiconductor (MIS) constructure galvanic displacement pattering Prussian blue/ silicon nanowires (PB/ SiNWs) electrode hydrogen peroxide （H2O2）
CLC: TB383.1
Type: PhD thesis
Year: 2010
Downloads: 281
Quote: 3
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Abstract

Recently, due to the unique semiconductor properties characteristics and the great potentials for developing various nano-devices such as nanoelectronics and nanosensors, silicon nanowires have attracted more and more attention.There exists a controversy about the formation mechanism of silicon nanowires (SiNWs) prepared by a chemical etching method assisted by metal ions (such as Ag+) in hydrogen fluoride-contained solution. To begin with, we discussed the difference between eletroless plating with galvanic displacement which is commonly adapted by others researches in the process of the SiNWs array preparation in HF solution containing noble metal ions.Firstly, a metal-insulator-semiductor (MIS) like structure had been put forward to explain the SiNWs array formation in the beginning of the thesis. In the galvanic displacement process, on one hand, the metal ions in the solution can extract the electrons from the silicon substrate and be reduced into metal nanoparticles or metal nanoclusters via the galvanic displacement. On the other hand, silicon substrates lose the electrons and are oxidized to silicon dioxide (SiO2). The reduced metal partcles located on the silicon oxide surface form the MIS-like structure. Hydrogen fluoride-contained solution will dissolve the silicon dioxide without metal covered and lead to the etching process to take place.Secondly, we succeeded in preparing the vertically aligned large-area SiNWs array in HF solution containing noble metal ions under the normal conditions (room temperature, latm.). Its expremental process is simple and the cost is decreased comparing with the the rigid experimental conditions, such as high temperature, high pressure, etc. in the previous literatures. Moreover, the optimal experimental parameters of prepaing SiNWs array are obtained by discussing the influence of various experimental conditions. These results further confirm that it is correct about the obove mentioned formation mechanism of SiNWs.Thirdly, in order to carry out the application in micro-and nano-devices and IC, the patterned SiNWs array is obtained by combining the pholithagraphy technology with chemical etching method. The silicon nitride layer is used as a mask. For silicon nitride layer will be etched away for a long etching time, we discuss the influence of etching time and obtain the optimal parameters during the process of prepaing SiNWs array. In addition, considering of the influence of patterns on the SiNWs etching, we put forward a fluid dynamics theory.Finally, the Prussian blue/silicon nanowires (PB/SiNWs) electrode is constructed successfully by modifying Prussian blue molecules on the surface of patterned SiNWs array. The electrochemical characteristic of this electrode was investigated by detecting hydrogen peroxide (H2O2) as a working electrode in a three-electrode electrochemical system. The results demonstrate that the electrode has an excellent catalytic resonse to H2O2 and is potential for electrochemical biosensors.

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