Aligned carbon nanotube field effect transistors by repeated compression-expansion cycles in Langmuir-Blodgett

Abstract

The superb advantages of carbon nanotubes (CNTs) cannot be exhibited completely by devices using random CNT networks as channel materials due to the large tube-to-tube contact resistance. Traditional Langmuir-Blodgett (LB) method with direct compression and dipping has little performance improvement for films due to defects of CNT orientation. Here an improved LB method with gradually increased surface pressure scheme has been proposed to fabricate aligned carbon nanotube field effect transistor (CNFET). Comparing the CNFETs with aligned CNT channel by LB method and the carbon nanotube thin film transistors (CNT-TFTs) with network CNT channel by spin-coating method, the device mobility increases from 2.044 cm 2/ (Vs) to 30.81 cm2/ (Vs). In addition, the CNFET shows a higher on-state current and a lower subthreshold swing. The performance improvement for the aligned CNTs by multiple compression and expansion cycling of the LB method is an important foundation for future development of CNT-based devices, especially flexible devices.