Abstracts Category : Other

Growth of Silicon Nanowire Mechanical Oscillators for Force-Detected Magnetic Resonance Measurements

by Xudong Liu

This thesis describes two ways to grow silicon nanowires with the catalyst gold (Au) by Chemical Vapor Deposition (CVD) system. One way to prepare catalyst is drop-casting gold nanoparticles solution, the other is making a gold pattern by electron beam lithography (EBL). The diameters of silicon nanowires can be controlled by size of gold nanoparticles in the solution or the size of gold nano-disks which is achieved by EBL. The position-controlled epitaxial growth of Si nanowires is realized by gold nano-disks pattern through EBL. Our Si nanowires are grown on the n-type Si (111) wafer at the same condition. The length is 12-17 m for Si nanowires 50-150nm in diameter. The taper of Si nanowires is 1 nm/m in both ways. We found that the growth rates are depend on the size of Si nanowires in drop-casting method, but independent in EBL method. Our purpose of growing Si nanowires is to use it as a cantilever in magnetic resonance force microscopy (MRFM) due to its high aspect ratio and low mechanical dissipation. Therefore, the Si nanowires is required to be vertical and smooth. A high vertical yield, 80%, is achieved by our growth recipe. With HCl added, the surface of Si nanowire is polished. Moreover, the lowest intrinsic dissipation of our nanowire is 610^(-15) kg/s at room temperature, and our Si nanowires can be used as a force sensor for MRFM.