The Study of Nano-optical Antenna Array Structure for Nano-device

Abstract

Nano antenna, coupling between terahertz level electro-magnetic wave and electri-cal signal, has been researched as an interest topic for terahertz communication and optoe-lectronics. In traditional antenna theory, the antenna length has strong relationship with wavelength. Especially, the formula that is a function of antenna size, wavelength, light velocity and frequency can be partly applied to terahertz communication. Therefore, multi-antenna structure with different length from micrometer to nanometer can have various resonant frequencies in ultra-high frequency region. However, the high resistance of metal nanostructure and the complicated fabrication process using ‘Top-down’ approach induce severe problems to the application in THz area. The purpose of this work is to grow Carbon nanotubes (CNTs) which have different lengths at specific points. To grow single multi-walled CNT (MWCNT) on selected po-sition, the patterned Ni catalyst and plasma enhanced chemical vapor deposition (PECVD) growth process were used. We investigated various CNT length formations with the con-trol of catalyst size, acetylene ratio and temperature. For the experiment of catalyst size control, single CNT has grown on the catalyst which size is below 300nm. Although low temperature growth appears lower growth rate, it shows higher yield ratio of single CNT growth. CNT length is proportional to catalyst size. CNT thickness and length are longer and thicker with increasing C2H2 gas ratio respectively. From optimized process condi-tions, we get single MWCNTs with various heights on selected points using one step CVD process. The expected resonance frequency is from 50 to 130 THz as monopole antenna concept. ⓒ 2013 DGIST