One-Step Fabrication of High-Performance All-SWNT Field- Effect Transistors by Patterned Growth Technique

Carbon nanotube field-effect transistor (CNT-FET) is a promising candidate for future electronic devices due to the excellent electronic properties. Recently, FET using CNTs as both electrodes and channel has been demonstrated [1]. The all-CNT devices can work on a flexible substrate without degrading their electrical properties [2,3] and may realize metal-free electronics. The fabrication technique is, however, complicated because it requires multiple CVD steps and ION/IOFF ratio is so far very low, not comparable with conventional CNT-FETs. We realized a high-performance all-SWNT FETs with a large ION/IOFF ratio and excellent transfer characteristics, fabricated by modifying our SAM-based patterning technique [4]. With an improved pattering technique of SAM film, metal catalysts are dip-coated in SAM removed area. By ACCVD technique patterned SWNT are grown on a Si substrate with 50 nm SiO2 layer. Here, vertically aligned and horizontal SWNTs, acting as electrodes and channel, respectively, are simultaneously synthesized in a one-step CVD process [Fig. 1(a)]. For measuring the FET properties in the back-gated configuration, the vertically-aligned SWNT films were used as source/drain electrodes as shown in Fig. 1(b). The resulting FET transfer characteristics show excellent properties with ION/IOFF ratio of 10 although the fabrication process is very simple. Here, the application of such all-SWNT FET will be discussed.