Medium-scale carbon nanotube thin-film integrated circuits on flexible plastic substrates

Abstract

The ability to form integrated circuits on flexible sheets of plastic enables attributes (for example conformal and flexible formats and lightweight and shock resistant construction) in electronic devices that are difficult or impossible to achieve with technologies that use semiconductor wafers or glass plates as substrates. Organic small-molecule and polymer-based materials represent the most widely explored types of semiconductors for such flexible circuitry. Although these materials and those that use films or nanostructures of inorganics have promise for certain applications, existing demonstrations of them in circuits on plastic indicate modest performance characteristics that might restrict the application possibilities. Here we report implementations of a comparatively high-performance carbon-based semiconductor consisting of sub-monolayer, random networks of single-walled carbon nanotubes to yield small- to medium-scale integrated digital circuits, composed of up to nearly 100 transistors on plastic substrates. Transistors in these integrated circuits have excellent properties: mobilities as high as 80 cm(2) V(-1) s(-1), subthreshold slopes as low as 140 m V dec(-1), operating voltages less than 5 V together with deterministic control over the threshold voltages, on/off ratios as high as 10(5), switching speeds in the kilohertz range even for coarse (approximately 100-microm) device geometries, and good mechanical flexibility-all with levels of uniformity and reproducibility that enable high-yield fabrication of integrated circuits. Theoretical calculations, in contexts ranging from heterogeneous percolative transport through the networks to compact models for the transistors to circuit level simulations, provide quantitative and predictive understanding of these systems. Taken together, these results suggest that sub-monolayer films of single-walled carbon nanotubes are attractive materials for flexible integrated circuits, with many potential areas of application in consumer and other areas of electronics.

Upper bound for the conductivity of nanotube networks

“…[1][2][3] One common route is to use films made by a disordered network of carbon nanotubes ͑NTs͒. [4][5][6][7][8][9] In this case, electrons move across the entire film by moving between NT in close proximity. The conductivity is limited by the tunneling between tubes, which introduces a significant inter-NT junction resistance.…”

Influence of Polymer Coating on Device Properties of Carbon Nanotube Field-Effect Transistors

“…Recently, high-performance flexible integrated circuits using carbon nanotube thin-film transistors (CNT-TFT) have been developed [1][2][3]. These devices have shown excellent device properties, however, both optical transparency and mechanical flexibility are limited due to the use of opaque metal electrodes and brittle oxide dielectrics.…”

High‐Throughput Fabrication of Flexible and Transparent All‐Carbon Nanotube Electronics

“…Notable progress has been made on the large‐scale fabrication of CNT thin films in recent years using floating catalyst chemical vapor deposition (CVD)1, 2, 11 or solution‐processed deposition methods 12, 13, 14. However, due to the lack of techniques that allow the deposition of liquid photoresists on an extremely large scale, CNT‐based electronic devices have been limited to the wafer‐scale12, 15, 16 or medium‐scale integration level 17, 18. Printing technology, such as inkjet printing,19, 20, 21, 22, 23, 24 screen printing,25, 26, 27, 28 and gravure printing,29, 30 in manufacturing electronics has drawn tremendous interest during the past few decades.…”