Parallel-Aligned SWNTs—Controlled Synthesis on Quartz and Characterization After Transfer to Slit-Structured Substrates

The outstanding properties of single-walled carbon nanotubes (SWNTs) are attributed to several factors, including their unique one-dimensional structure, peculiar electronic structure, high electron mobility and thermal conductivity. Based on these extraordinary properties, SWNTs are being widely explored in various fields, including electronics such as field effect transistors, transparent conductive films, light emitting devices and nanoscale sensors.<br/>Due to the direct relationship between the chirality of SWNTs and electron-related physical properties, growth parameters such as growth temperature, catalyst composition, catalytic particle size, flow rate and type of feedstock should be adjusted during growth to obtain SWNTs with pre-designed chirality.<br/>In order to realize the parallel growth of SWNTs with single chirality, we report here our preliminary results on the parallel growth of single SWNTs on quartz substrate using conventional horizontal chemical vapor deposition (CVD) and successive transfer from quartz wafer to slit substrate for precise characterization of the chirality or diameter of SWNTs using Raman spectroscopy, photoluminescence, atomic force microscopy and transmission electron microscopy.<br/>To facilitate the lattice-guided growth of SWNTs, we used single crystal quartz wafers and optimized the annealing conditions to achieve a high degree of horizontal alignment. We investigated the effects of growth temperature, growth time, and catalyst particle size on the parallel alignment and density of SWNTs, recognizing that improved alignment can enhance performance in nanoelectronics and sensors. Since suspended SWNTs produce significantly enhanced signals in optical spectroscopy, we also fabricated slit-structured substrates to obtain obvious results from parallel-aligned SWNTs after transfer to these substrates. We have optimized cleanroom processes for the fabrication of the slit substrates. Finally, we will present the successful growth of parallel-aligned SWNTs, their transfer to slit-structured substrates, and characterization results of the transferred SWNTs.