Ultrathin films of single-walled carbon nanotubes (SWNTs) represent an attractive, emerging class of material, with properties that can approach the exceptional electrical, mechanical, and optical characteristics of individual SWNTs, in a format that, unlike isolated tubes, is readily suitable for scalable integration into devices. These features suggest the potential for realistic applications as conducting or semiconducting layers in diverse types of electronic, optoelectronic and sensor systems. This article reviews recent advances in assembly techniques for forming such films, modeling and experimental work that reveals their collective properties, and engineering aspects of implementation in sensors and in electronic devices and circuits with various levels of complexity. A concluding discussion provides some perspectives on possibilities for future work in fundamental and applied aspects.

http://www.ifc.dicp.ac.cn/library/cailiao/pdf1/11.pdf

Ultrathin Films of Single-Walled Carbon Nanotubes for Electronics and Sensors: A Review of Fundamental and Applied Aspects

Two-dimensional (2D) materials have generated great interest in the past few years as a new toolbox for electronics. This family of materials includes, among others, metallic graphene, semiconducting transition metal dichalcogenides (such as MoS2), and insulating boron nitride. These materials and their heterostructures offer excellent mechanical flexibility, optical transparency, and favorable transport properties for realizing electronic, sensing, and optical systems on arbitrary surfaces. In this paper, we demonstrate a novel technology for constructing large-scale electronic systems based on graphene/molybdenum disulfide (MoS2) heterostructures grown by chemical vapor deposition. We have fabricated high-performance devices and circuits based on this heterostructure, where MoS2 is used as the transistor channel and graphene as contact electrodes and circuit interconnects. We provide a systematic comparison of the graphene/MoS2 heterojunction contact to more traditional MoS2-metal junctions, as well as ...

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Graphene/MoS2 Hybrid Technology for Large-Scale Two-Dimensional Electronics

Two-dimensional (2D) materials have generated great interest in the past few years as a new toolbox for electronics. This family of materials includes, among others, metallic graphene, semiconducting transition metal dichalcogenides (such as MoS2), and insulating boron nitride. These materials and their heterostructures offer excellent mechanical flexibility, optical transparency, and favorable transport properties for realizing electronic, sensing, and optical systems on arbitrary surfaces. In this paper, we demonstrate a novel technology for constructing large-scale electronic systems based on graphene/molybdenum disulfide (MoS2) heterostructures grown by chemical vapor deposition. We have fabricated high-performance devices and circuits based on this heterostructure, where MoS2 is used as the transistor channel and graphene as contact electrodes and circuit interconnects. We provide a systematic comparison of the graphene/MoS2 heterojunction contact to more traditional MoS2-metal junctions, as well as a theoretical investigation, using density functional theory, of the origin of the Schottky barrier height. The tunability of the graphene work function with electrostatic doping significantly improves the ohmic contact to MoS2. These high-performance large-scale devices and circuits based on this 2D heterostructure pave the way for practical flexible transparent electronics.

/pdf/graphene-mos2-hybrid-technology-for-large-scale-two-3dg0f0mu9d.pdf

Graphene-MoS2 Hybrid Technology for Large-Scale Two-Dimensional Electronics

IEEE International Solid-State Circuits Conference

In this article, we report only 10 atomic layer thick, high mobility, transparent thin film transistors (TFTs) with ambipolar device characteristics fabricated on both a conventional silicon platform as well as on a flexible substrate. Monolayer graphene was used as metal electrodes, 3–4 atomic layers of h-BN were used as the gate dielectric, and finally bilayers of WSe2 were used as the semiconducting channel material for the TFTs. The field effect carrier mobility was extracted to be 45 cm2/(V s), which exceeds the mobility values of state of the art amorphous silicon based TFTs by ∼100 times. The active device stack of WSe2–hBN–graphene was found to be more than 88% transparent over the entire visible spectrum and the device characteristics were unaltered for in-plane mechanical strain of up to 2%. The device demonstrated remarkable temperature stability over 77–400 K. Low contact resistance value of 1.4 kΩ-μm, subthreshold slope of 90 mv/decade, current ON–OFF ratio of 107, and presence of both electr...

All Two-Dimensional, Flexible, Transparent, and Thinnest Thin Film Transistor

Due to their excellent electrical properties, metallic carbon nanotubes are promising materials for interconnect wires in future integrated circuits. Simulations have shown that the use of metallic carbon nanotube interconnects could yield more energy efficient and faster integrated circuits. The next step is to build an experimental prototype integrated circuit using carbon nanotube interconnects operating at high speed. Here, we report the fabrication of the first stand-alone integrated circuit combining silicon transistors and individual carbon nanotube interconnect wires on the same chip operating above 1 GHz. In addition to setting a milestone by operating above 1 GHz, this prototype is also a tool to investigate carbon nanotubes on a silicon-based platform at high frequencies, paving the way for future multi-GHz nanoelectronics.

A 1 GHz integrated circuit with carbon nanotube interconnects and silicon transistors.

Carbon-based nanomaterials such as metallic single-walled carbon nanotubes, multiwalled carbon nanotubes (MWCNTs), and graphene have been considered as some of the most promising candidates for future interconnect technology because of their high current-carrying capacity and conductivity in the nanoscale, and immunity to electromigration, which has been a great challenge for scaling down the traditional copper interconnects. Therefore, studies on the performance and optimization of carbon-based interconnects working in a realistic operational environment are needed in order to advance the technology beyond the exploratory discovery phase. In this paper, we present the first demonstration of graphene interconnects monolithically integrated with industry-standard complementary metal-oxide-semiconductor technology, as well as the first experimental results that compare the performance of high-speed on-chip graphene and MWCNT interconnects. The graphene interconnects operate up to 1.3-GHz frequency, which is a speed that is commensurate with the fastest high-speed processor chips today. A low-swing signaling technique has been applied to improve the speed of carbon interconnects up to 30%.

/pdf/fully-integrated-graphene-and-carbon-nanotube-interconnects-81qtkxuv5p.pdf

Fully Integrated Graphene and Carbon Nanotube Interconnects for Gigahertz High-Speed CMOS Electronics

In one embodiment, a semiconductor integrated circuit includes a first resistive-change element, a second resistive-change element and a first switching element. The first resistive-change element includes one end having a first polarity connected to a first power source. The first resistive-change element includes another end having a second polarity connected to an output node. The second resistive-change element includes one end having the second polarity connected to the output node. The first switching element includes a first terminal connected to another end of the second resistive-change element. The first switching element includes a second terminal connected to a second power source.

Semiconductor Integrated Circuit

In this work, because of the high-amplitude random noise at high frequency from the SiN MOSFET, we need only a single amplifier and A/D converter, and the amplifier area is decreased.

1200μm 2 Physical Random-Number Generators Based on SiN MOSFET for Secure Smart-Card Application

We integrate carbon nanotube (CNT) fabrication with standard commercial CMOS very large scale integration on a single substrate suitable for emerging hybrid nanotechnology applications. This cointegration combines the inherent advantages of CMOS and CNTs. These emerging applications include CNT optical, biological, chemical, and gas sensors that require complex CMOS electronics for sensor control, calibration, and signal processing. We demonstrate the successful cointegration on a single chip with a vehicle circuit, a two-transistor cascode megahertz amplifier utilizing both silicon n-channel MOSFET and CNT transistors with a total power consumption of 62.5 muW.

Shinichi Yasuda

Papers

A 1 GHz integrated circuit with carbon nanotube interconnects and silicon transistors.

Fully Integrated Graphene and Carbon Nanotube Interconnects for Gigahertz High-Speed CMOS Electronics

Semiconductor Integrated Circuit

1200μm 2 Physical Random-Number Generators Based on SiN MOSFET for Secure Smart-Card Application

Monolithic Integration of CMOS VLSI and Carbon Nanotubes for Hybrid Nanotechnology Applications