Si nanowires: synthesis, functionalization and applications

Abstract

Silicon nanowires (SiNWs) have become the focus of intensive research as one of the most technologically important building blocks. In particular, millimeter-long SiNWs whose lengths extend over macroscopic length scales and reach the size of integrated systems, could be exploited as the basis for complex electronic circuits and functional nanosystems by the direct integration of a number of device elements into a single nanostructure. Here I will present the approach to synthesize the millimeter-long SiNWs, and to functionalize the NW surfaces for device applications. Quantitative analysis showed that NW growth can be continued at a high growth rate of ~31 μm/min without terminating VLS process for 1-hr, and the longest ones reached 3.5 mm and their aspect ratios extend up to ~100,000 while the diameters are uniform along the wires. In addition, electrical doping was introduced during the synthesis, and transport measurements of the wires demonstrated uniform field-effect transistor (FET) properties over the entire lengths of these nanowires. We converted the multiple FETs into biological sensor arrays by functionalizing SiNW surfaces with monoclonal antibodies (mAbs), and studied the multiplexed electrical detection of cancer markers. Finally, SiNWs were further coupled with functional oxides to demonstrate non-volatile memory devices.