Logic circuits composed of flexible carbon nanotube thin. Flexible carbon nanotube circuits made more reliable. Logic gates are constructed on individual carbon nanotubes via a dopingfree approach and with a single power supply at voltages as low as 0. Complementary metaloxidesemiconductor inverters exhibited voltage. Of particular interest are logic gates that form the basis of computer logic. Here we demonstrate that a significant reduction in the use of fieldeffect transistors can be achieved by constructing carbon nanotubebased integrated circuits based on a. Carbon nanotube transistors for biosensing applications. Kauppinen, shigeru kishimoto, takashi mizutani and yutaka ohno supplementary 1. However, to date, circuits built with carbon nanotubes have overlooked key aspects of a practical logic technology and have stalled at simple functionality demonstrations. Design guidelines for metalliccarbonnanotube tolerant. The ambipolar cnt transistors automatically configure themselves to play a role as an ntype or ptype transistor in a logic circuit depending on the supply voltage vdd and ground. Introduction to carbon nanotubes carbon nanotubes were discovered in 1991 by sumio iijima of nec and are effectively long, thin cylinders of graphite, which you will be familiar with as the material in a pencil or as the basis of some lubricants. Then they coated the tubes with their encapsulation layers.
A new technique is used for achieving local gates in nanotube. Besides, due to the use of unsorted carbon nanotubes and dep, which attracts mainly metallic nanotubes,24 the resulting rf transistor exhibits almost no gate. With the recent demonstration of nanotube based prototypes of logic circuits and. Logic circuits with carbon nanotube transistors adrian bachtold, peter hadley, takeshi nakanishi, cees dekker we demonstrate logic circuits with. Toward highperformance digital logic technology with. We discuss our recent efforts to develop high performance carbon nanotube field effect transistors cntfets and logic circuits.
Flexible, highperformance carbon nanotube integrated circuits dongming sun, marina y. Adaptive logic circuits with dopingfree ambipolar carbon. Extremely bendable, highperformance integrated circuits. For the first time a flexible cnt circuit has been doped to create a complimentary circuit photo. A nor nand gate is adaptively converted to a nand nor gate. Jayanthy2 1research scholar, sathyabama university, tamil nadu, india. Using the encapsulated carbon nanotubes, hersams team successfully designed and fabricated arrays of working sram circuits. This alignment is accomplished by incorporating local metal gate structures and sorted semiconducting carbon nanotubes.
Singlewalled carbon nanotubes swcnts have been shown to exhibit excellent electrical properties, such as ballistic transport over several hundred nanometers at room temperature. Modularized construction of general integrated circuits on. Ultralow power carbon nanotube logic circuits 20140082. Voltage mirror circuit by carbon nanotube field effect transistors for mirroring dynamic random access memories in multiplevalued logic and fuzzy logic. Zhang, imperfectionimmune vlsi logic circuits using carbon nanotube fets, ieeeacm design automation and test in europe, 2009. Since only semiconducting nanotubes yield transistors, the metallic nanotubes are. The passtransistor logic configurarion provides a significant simplification of the carbon nanotubebased circuit design, a higher potential circuit speed and a significant reduction in power. In particular, printed thinfilm transistors tfts that utilize carbon nanotubes cnts have exhibited high onstate currents, mobility, and current onoff ratios at low operating voltages. In order to demonstrate truly integrated nanotube circuits and waferscale fabrication, technological components such as waferscale synthesis and transfer of aligned nanotubes, and integrated submicronscale device fabrication and tuning, are highly desired for the highperformance integrated nanotube circuits. One approach they are trying involves designing circuits based on electronic fibers, known as carbon nanotubes cnts, instead of rigid silicon chips. Pdf highspeed logic integrated circuits with solutionprocessed. A cmoslike inverter was integrated by using ambipolar carbon nanotube cnt transistors without doping. Carbon nanotube circuits are back in the running as a.
Even more exciting is the possibility of building logic gates out of a single nanotube or nanotube bundle. While there has been significant progress at a singledevice level, a major gap exists between such results and their transformation into vlsi cnfet technologies. By improving the metal nanotube contacts the characteristics of the cntfets are greatly enhanced. Highspeed logic integrated circuits with solutionprocessed selfassembled carbon nanotubes. This letter reports on the realization of logic circuits employing solutionprocessed networks of singlewalled carbon nanotubes. Flexible, highperformance carbon nanotube integrated circuits.
Logic circuits with carbon nanotube transistors science. Design guidelines for metalliccarbonnanotubetolerant digital logic circuits jie zhang, nishant p. Logic circuits based on individual semiconducting and. A defect model for metallic carbon nanotubes in cellbased. Carbon nanotube based logic gates structure for low. Carbon nanotube transistors and logic circuits sciencedirect. We demonstrate logic circuits with fieldeffect transistors based on single carbon nanotubes. Odom et alsinglewalled carbon nanotubes 205 dices determine whether a swnt will be a metal or a semiconductor. Analysis shows that the performance of ptype cntfets is already competitive to that of silicon pmosfets. Design of digital logic circuits using carbon nanotube. Molecular scale devices including diodes, bistable switches, carbon nanotubes, and nanowires have been fabricated and characterized in chemistry labs. Carbon nanotube inter and intramolecular logic gates.
Pdf device study, chemical doping, and logic circuits. Us7985906b2 nanotubebased switching elements and logic. Request pdf logic circuits with carbon nanotubes a new technique is used for achieving fieldeffect transistors based on a single semiconducting nanotube and with a gate that is local and that. Carbon nanotubes cnts are quasi onedimensional nano. Carbon nanotube transistors for biosensing applications g. The digital logic circuits use ptype and ntype carbon nanotube based transistors which have tuned threshold voltages that enable ultralow power operation. Under one embodiment of the invention, a boolean logic circuit includes at least one input terminal and an output terminal, and a network of nanotube switching elements electrically disposed between said at least one input terminal and said output terminal. Carbon nanotubes are unique tubular structures of nanometer diameter and large lengthdiameter ratio. Growing carbon nanotubes results in a mix of metallic and semiconducting forms, which is undesirable, and the number of nanotubes must be made quite uniform from transistor to transistor in order. Nanotubebased switching elements and logic circuits are disclosed. The nanotubes had diameters between 2 and 20 nm, and lengths of several micrometers. Researchers shrink carbon nanotube circuits chemical. An integrated logic circuit assembled on a single carbon. To build such logic circuits, one needs nanotube devices that use electrons ntype cntfets and holes ptype as the carriers of electricity.
In this article, we demonstrate a reliable process to fabricate high speed cnt cmos integrated circuits on. Carbon nanotubes cnts are now wellestablished as efficient channels for field effect transistors. This was challenging previously with carbon nanotube circuits due to the lack of control of the threshold voltages of nanotube transistors. Inconsistencies in quality also plague researchers trying to make circuits using transistors consisting of tens or hundreds of carbon nanotubes. Logic circuits with carbon nanotube transistors duke computer.
In this paper, highperformance backgated carbon nanotube fieldeffect transistors based on transferred aligned carbon nanotubes were fabricated and studies found that the onoff ratio can reach 107 and the current density can reach 1. Researchers have demonstrated a new carbon nanotube cntbased logic device that consumes just 0. Carbon nanotubes are distinctive because of their intriguing. Our device layout features local gates that provide excellent capacitive coupling between the gate and nanotube, enabling strong electrostatic doping of the nanotube from pdoping to ndoping and the study of the nonconventional longrange screening of charge along the onedimensional nanotubes. Patil, subhasish mitra stanford university, stanford, ca abstract metallic carbon nanotubes cnts create sourcedrain shorts in carbon nanotube field effect transistors cnfets, causing excessive leakage, degraded noise margin and delay variation. Stable logic operation of fiberbased singlewalled carbon nanotube transistor circuits toward threadlike cmos circuitry jae sang heo 1,2, kyungtae kim 1, seokgyu ban 1, yoonjeong kim 1, daesik kim 3, taehoon kim 3, yongtaek hong 3, insoo kim 2 and sung kyu park 1, 1 school of electrical and electronic engineering, chungang university. Carbon nanotube fieldeffect transistors and logic circuits. Carbon nanotubes are usually produced as a mixture of semiconducting and metallic nanotubes. In this paper ambipolar cntfets are used to design basic logic circuits.
Pdf in this paper, we present recent advances in the understanding of the properties of semiconducting single wall carbon nanotube and in the. Power consumption of logic circuits in ambipolar carbon nanotube technology m. Carbon nanotube transistors go headtohead with silicon. Therefore the leakage current and power dissipation becomes increasingly more focused in vlsi circuit design. Carbon nanotube field effect transistor based digital. Stable logic operation of fiberbased singlewalled carbon. However, many of the metallic carbon nanotubes can in fact be used to fabricate load resistors, and these can be integrated with transistors based on semiconducting nanotubes to design unipolar circuits with good static and dynamic performance. Our device layout features local gates that provide excellent capacitive coupling between the gate and nanotube, enabling strong electrostatic doping of the nanotube from p doping to n doping and the study of the nonconventional longrange screening of charge along the onedimensional nanotubes. To create the encapsulated carbon nanotubes, the team first deposited the carbon nanotubes from a solution previously developed in hersams lab.
Logic circuits with carbon nanotube transistors request pdf. An important next step is the fabrication of integrated circuits on. Logic circuits using solutionprocessed singlewalled. Toward highperformance digital logic technology with carbon.
Printable flexible electronics is considered as one of the most rapidly developing technologies because it has the potential to be scalable and costeffective 1,2,3,4,5. The carbon nanotube fieldeffect transistor cntfet is a good alternative to the cmos transistors for the implementation of logic circuits due to its high performance and low power consumption 6. Afm image of carbon nanotube network and distribution of diameters of nanotubes. Graphite is made up of layers of carbon atoms arranged in a hexagonal lattice, like chicken wire see.
Nano letters carbon nanotube inter and intramolecular. Our device layout features local gates that provide. This presentation will briefly describe the challenges to future transistor scaling, highlight the advantages of employing carbon nanotubes for digital logic and describe the recent progress in. Cntfet utilizes a semiconducting carbon nanotube cnt channel controlled by isolated electrostatic gates. In principle, the combined properties of both kinds of nanotubes can form a unique set of building blocks for future electronics. We constructed basic logic gates inverter, nand and nor with n and ptype fieldeffect transistors fabricated by solutionbased chemical doping. Flexible cmos integrated circuits based on carbon nanotubes with. There was a time, not so long ago, when carbon nanotubes cnts were. Using spatially resolved doping we implemented this logic function on a single nanotube bundle. Impact of manufacturing defects on carbon nanotube logic. We demonstrate the use of dopants to tune the charge carrier density of carbon nanotubes films and. Pdf carbon nanotube fieldeffect transistors and logic circuits. Highly noiseresistant logic gates are needed for largescale circuits.
Circuit level modeling and detection of metallic carbon nanotube defects in carbon nanotube fets. Exclusiveor gate with a single carbon nanotube maxplanckinstitut. Fieldeffect transistors fets made from individual tubes show dc performance specifications rivaling those of stateoftheart silicon devices. Abstract we demonstrate logic circuits with fieldeffect transistors based on single carbon nanotubes. The network of nanotube switching elements effectuates a boolean. Power consumption of logic circuits in ambipolar carbon. Realizing carbon nanotube integrated circuits news. It demonstrates ptype or ntype switching behavior depending upon the polaritygate voltage. Nanoelectronics circuits built with components on the scale of 10nm seem to be the most promising successor to lithographic based ics. Carbon nanotube field effect transistors cnfets, consisting of semiconducting single walled carbon nanotubes cnts, show great promise as extensions to silicon cmos. Carbon nanotube logic device operates on subnanowatt power. Monitoring the growth of carbon nanotubes by carbon.