Sub-20 nm Short Channel Carbon Nanotube Transistors

Seidel, Robert; Graham, Andrew; Kretz, Johannes; Rajasekharan, B.; Duesberg, Georg S.; Liebau, M.; Unger, E.; Kreupl, Franz; Hoenlein, W.

doi:10.1021/nl048312d

Cited by 132 publications

(82 citation statements)

References 11 publications

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“…There are many studies that focus on nanodevices with the integration of nanogap electrodes and organic molecules (small molecules, [153] oligomers, [154,155] polymers, [156] fullerenes, [8,157] and biomolecules, [158][159][160][161] etc.) or other nanometer-sized components (CNTs, [162] nanocrystals, [84,163] etc.) that effectively function as switches, rectifiers, memories, and transistors.…”

Section: Applicationsmentioning

confidence: 99%

Nanogap Electrodes

2009

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Nanogap electrodes (namely, a pair of electrodes with a nanometer gap) are fundamental building blocks for the fabrication of nanometer‐sized devices and circuits. They are also important tools for the examination of material properties at the nanometer scale, even at the molecular scale. In this review, the techniques for the fabrication of nanogap electrodes, the preparation of assembled devices based on the nanogap electrodes, and the potential application of these nanodevices for analysis of material properties are introduced. The history, the research status, and the prospects of nanogap electrodes are also discussed.

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Section: Applicationsmentioning

confidence: 99%

Nanogap Electrodes

2009

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“…25,26 At high electric fields, the electrons gain enough energy to emit optical phonons which have stronger electron-phonon coupling and therefore the mean free path is reduced to 15 nm. 26 The extraordinary high mobility in combination with their resilience to high current densities, 27 simple integration with various gate dielectrics 28 and good electrostatics due to their small diameter makes CNTs an attractive option for various electronic devices such as high speed transistors and Schottky diodes.…”

Section: Electronic Properties Of Carbon Nanotubesmentioning

confidence: 99%

Schottky barriers in carbon nanotube-metal contacts

Svensson

Campbell

2011

Journal of Applied Physics

178

134

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Contact resistance between metal and carbon nanotube interconnects: Effect of work function and wettability Applied Physics Letters 95, 264103 (2009) Semiconducting carbon nanotubes (CNTs) have several properties that are advantageous for field effect transistors such as high mobility, good electrostatics due to their small diameter allowing for aggressive gate length scaling and capability to withstand high current densities. However, in spite of the exceptional performance of single transistors only a few simple circuits and logic gates using CNTs have been demonstrated so far. One of the major obstacles for large scale integration of CNTs is to reliably fabricate p-type and n-type ohmic contacts. To achieve this, the nature of Schottky barriers that often form between metals and small diameter CNTs has to be fully understood. However, since experimental techniques commonly used to study contacts to bulk materials cannot be exploited and studies often have been performed on only single or a few devices there is a large discrepancy in the Schottky barrier heights reported and also several contradicting conclusions. This paper presents a comprehensive review of both theoretical and experimental results on CNT-metal contacts. The main focus is on comparisons between theoretical predictions and experimental results and identifying what needs to be done to gain further understanding of Schottky barriers in CNT-metal contacts.

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“…[1][2][3][4][5][6][7][8][9][10][11][12] While much has been done to achieve high performance p-type nanotube FETs through contact optimization, dielectric integration and lateral scaling, progress on nFETs has been slow partly due to the difficulty in affording low Schottky (SB) contacts for high on-states and at the same time achieving high on/off ratios with small diameter (or large bandgap) tubes. 7 Here, by invoking chemical doping, high-κ dielectrics and new device design, we demonstrate n-type SWNT FETs with performance matching or approaching the best p-type nanotube FETs and surpassing the state-of-the-art Si n-MOSFET.…”

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High Performance n-Type Carbon Nanotube Field-Effect Transistors with Chemically Doped Contacts

et al. 2005

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SWNT synthesis, 13 atomic layer deposition (ALD) of HfO 2 10,14,15 (t ox =8nm) and details of device fabrication are similar to those described previously. In Fig.1, we first show the electrical properties of a back-gated (t SiO2 =10nm, Fig. 1a) semiconducting SWNT (d~1.4 to 1.5 nm, channel length L~150 nm between Pd source/drain S/D) device before and after K-doping (details of doping described previously [16][17][18] ). The as-made device is a p-type FET with I on~ 5µA and linear conductance of G on~0 .3 e 2 /h (Fig. 1b). technique. 10,14,15 The nanotube segments outside the gate stack are fully exposed for K vapor doping to form n + regions (Fig.2a). ALD of HfO 2 on SWNTs provides excellent electrostatic modulation of the channel conductance without degrading the transport property of the 1D nanotube channels. 3,9,10 This is another key element in affording high performance n-type SWNT FETs.Prior to K doping, the devices operated as p-MOSFETs (Fig. 2b blue curve) when the two ends of the tube were electrostatically hole-doped by a back-gate. 21 Upon exposure to K vapor in vacuum, the S/D regions became n-doped while the top-gated channel regions remained intrinsic due to blocking of K by the gate stack. This afforded n + -i-n + n-type nanotube MOSFETs. The electrical properties of a SWNT (d~1.6-1.7 nm; E g ~0.55eV) MOSFET before (p-type) and after K-doping (n-type) in vacuum are shown showed near-symmetrical characteristics with similar on-currents I on~ 8 µA at V ds =0.5 (Fig. 2c). The transconductance were (dI ds /dV gs ) max ~ 20 µS and ~10 µS for n-and pFETs respectively. Both devices exhibited excellent switching characteristics with subthreshold swings S=dI ds /dV gs~7 0-80 mV/decade (Fig. 2b), near the theoretical limit of S~60 mV/decade. Note that at V ds =0.5V, a high I on /I off ~10 6 was achieved for the nanotube n-MOSFET with no significant ambipolar p-channel conduction (Fig. 2b red curve). These characteristics are the best reported to-date for n-type nanotube FETs enabled by the MOSFET geometry 6,22 with chemically doped S/D, high-κ dielectrics and transparent metal-tube contacts. In such a MOSFET-like geometry the gate electric fields result in bulk switching of the nanotube directly under the gate-stack with little effect to the Schottky barriers at the metal-tube junctions.We next investigated the effects of the contacts doping level on the electrical characteristics of our nanotube n-FETs. The doping level was varied by adjusting the exposure time of the devices to K atoms. Fig. 3a (dashed curve) shows the switching properties for the same device in Fig.2 but at a higher degree of n-doping of the S/D contacts. The on-current of the device increased from ~ 8µA to 15 µA at V ds =0.5 V (Fig. 3b), attributed to further enhanced transparency at the Pd-tube junctions and lower series resistance in the n + nanotube segments. The on-current increase was, however, accompanied by a more obvious ambipolar p-channel conduction, an increase in the minimum leakage current (I min ) and a reduction of I ...

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Sub-20 nm Short Channel Carbon Nanotube Transistors

Cited by 132 publications

References 11 publications

Nanogap Electrodes

Nanogap Electrodes

Schottky barriers in carbon nanotube-metal contacts

High Performance n-Type Carbon Nanotube Field-Effect Transistors with Chemically Doped Contacts

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