Logic circuits composed of flexible carbon nanotube thin-film transistor and ultra-thin polymer gate dielectric

Abstract

Printing electronics has become increasingly prominent in the field of electronic engineering because this method is highly efficient at producing flexible, low-cost and large-scale thin-film transistors. However, TFTs are typically constructed with rigid insulating layers consisting of oxides and nitrides that are brittle and require high processing temperatures, which can cause a number of problems when used in printed flexible TFTs. In this study, we address these issues and demonstrate a method of producing inkjet-printed TFTs that include an ultra-thin polymeric dielectric layer produced by initiated chemical vapor deposition (iCVD) at room temperature and highly purified 99.9% semiconducting carbon nanotubes. Our integrated approach enables the production of flexible logic circuits consisting of CNT-TFTs on a polyethersulfone (PES) substrate that have a high mobility (up to 9.76 cm2 V−1 sec−1), a low operating voltage (less than 4 V), a high current on/off ratio (3 × 104), and a total device yield of 90%. Thus, it should be emphasized that this study delineates a guideline for the feasibility of producing flexible CNT-TFT logic circuits with high performance based on a low-cost and simple fabrication process.

The State of HiPco Single-Walled Carbon Nanotubes in 2019

“…Carbon nanotubes have been at the forefront of materials research for the better part of three decades now, with single-walled carbon nanotubes (SWCNTs) taking precedence over their multi-walled variants. Indeed, a major part of this interest has been due to the unique electronic properties possessed by SWCNTs, dictated by the chirality of the individual carbon nanotube [1,2], that has led to potential applications including solar power [3], fuel cells [4], water filtration [5], and thin-film transistors [6]. As-synthesized SWCNTs have also been further analyzed via various methods of separation to develop enriched ensembles of metallic-and semiconducting-SWCNTs [7], to further facilitate research and a move from the lab to the retail market.…”

Spatial network conduction in carbon nanotube and Ag-Ag₂S-Ag atomic switch network device platforms

“…Network CNT FET mobilities tend to be 10 cm 2 /Vs to 20 cm 2 /Vs [12,26,51,52], 2-3 orders of magnitude lower than a single CNT FET devices which have been shown to have mobilities of 79 000 cm 2 /Vs [53].…”

“…Thin film networks of CNTs have been used to fabricate FETs with on-off ratios of >10 3 , and mobilities of ∼10 cm 2 V −1 s −1 [25]. While these metrics not as impressive as single CNTs, the scalable solution processing has seen them applied in integrated circuit and sensing platforms [10,11,26,47,51,56,74,102,103,110].…”

“…The need to 'write' the pattern desired by scanning an electron beam means that it is unfeasible for large or repeat patterning. A large section of the literature thus is focused on larger scale CNT structures such as ordered arrays or random networks of CNTs in a film [10,11,26,47,51,56,74,102,103,110].…”

“…Networks of CNTs can be fabricated by growing large numbers of tubes directly on the substrate [14,25,58], or using solution-based methods to deposit pre-grown CNTs on to the substrate. Solution deposition methods such as inkjet printing [5,51] and directed transfer using surface functionalisation [26,52,84,85,87,91], have spurred research into using CNT TFTs as a scalable fabrication path for continued device application research [10,48,51]. These networks have been fabricated at wafer scale [70], or restricted to regions on the order of a single tube length, offering scope for tailoring of the film size to the requirements of the desired application.…”