플라즈마 화학기상증착법으로 제작된 네트워크 탄소나노튜브 트렌지스터의 subthreshold 특성 분석

Abstract

Since their discovery in 1991 by Iijima [1], Carbon nanotubes have been of great interest due to their unique properties. Numerous investigators have reported remarkable physical and electrical properties of carbon nanotubes. Depending on geometrical structure, carbon nanotubes can be metallic or Semiconducting. From their unique electrical properties, the applications of the carbon nanotubes in electronic devices including field effect transistors, single electron transistor, logic circuit could have been realized. In this study, we first discuss the physical and electrical properties of carbon nanotubes. We then review the several synthesis techniques such as arc discharge, laser ablation and chemical vapor deposition. In particular, we focus plasma enhanced vapor deposition that can easily scale down the fraction of metallic nanotubes in nanotube network. Then we discuss the transistors with single carbon nanotube or carbon nanotube network. Finally, we investigated the subthreshold slope of random network carbon nanotube transistors with different geometries and passivations. Single-wall carbon nanotubes with lengths of 1-2 μm were grown by plasma-enhanced chemical vapor deposition to form the transistor channels. A critical channel length, where the subthreshold slope was saturated, of 7 μm was obtained. This was due to the percolational behavior of the nanotube random networks. With the dielectric passivation, the subthreshold slope was dramatically reduced from 9 V/decade to 0.9 V/decade by reducing interfacial trap sites which then reduced the interface capacitance between the nanotube network and the gate dielectric.