Ballistic carbon nanotube field-effect transistors

Javey, Ali; Guo, Jing; Wang, Qian; Lundstrom, Mark; Dai, Hongjie

doi:10.1038/nature01797

Cited by 2,929 publications

(2,318 citation statements)

References 27 publications

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“…High saturation currents, limited by optical phonon emission, allow large biases, I ds ∼ 20 µA at V ds 1 V in short nanotubes [12,13]. The above numbers and the good gate coupling explain the large transconductances, g m ∼ I ds /∆ 10 µS, observed in dc experiments [1]. In the ac, an intrinsic limitation is given by the transit frequency f T = g m /2πC g , where C g is the gate-nanotube capacitance.…”

Section: Pacs Numbersmentioning

confidence: 84%

Single Carbon Nanotube Transistor at GHz Frequency

et al. 2008

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We report on microwave operation of top-gated single carbon nanotube transistors. From transmission measurements in the 0.1-1.6 GHz range we deduce device transconductance gm and gatenanotube capacitance Cg of micro-and nanometric devices. A large and frequency-independent gm ∼ 20 µS is observed on short devices which meets best dc results. The capacitance per unit gate length ∼ 60 aF/µm is typical of top gates on conventional oxide with ǫ ∼ 10. This value is a factor 3-5 below the nanotube quantum capacitance which, according to recent simulations, favors high transit frequencies fT = gm/2πCg. For our smallest devices, we find a large fT ∼ 50 GHz with no evidence of saturation in length dependence. PACS numbers:Carbon nanotube field effect transistors (CNT-FETs) are very attractive as ultimate, quantum limited devices. In particular, ballistic transistors have been predicted to operate in the the sub-THz range [1,2]. Experimentally, a state-of-the-art cut-off frequency of 30 GHz has been reached in a low impedance multi-nanotube device [3], whereas 8 GHz was achieved with a multigate single nanotube transistor [4]. Indirect evidence of microwave operation were also obtained in experiments based on mixing effects or channel conductance measurement in single nanotubes [5,6,7,8,9].The extraordinary performances of nanotubes as molecular field effect transistors rely on a series of unique properties. High-mobility "p-doped" single walled nanotubes can be obtained by CVD-growth, with a semiconducting gap ∆ ∼ 0.5-1 eV (diameter 1-2 nm) [10]. Low Schottky-barrier contacts, with Pd metallisation, and quasi-ballistic transport result in a channel resistance R ds approaching the quantum limit, h/4e 2 = 6.5 kΩ for a 4-mode single walled nanotube [11]. High saturation currents, limited by optical phonon emission, allow large biases, I ds ∼ 20 µA at V ds 1 V in short nanotubes [12,13]. The above numbers and the good gate coupling explain the large transconductances, g m ∼ I ds /∆ 10 µS, observed in dc experiments [1]. In the ac, an intrinsic limitation is given by the transit frequency f T = g m /2πC g , where C g is the gate-nanotube capacitance. Here C g = C geo C Q /(C geo + C Q ) is the series combination of the quantum and geometrical capacitances, C Q and C geo . Ultrathin oxide coating in CNTFETs allows to approach the quantum limit with a capacitance per unit gate length l g , C geo /l g > C Q /l g = * Electronic address: Bernard.Placais@lpa.ens.fr

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Section: Pacs Numbersmentioning

confidence: 84%

Single Carbon Nanotube Transistor at GHz Frequency

et al. 2008

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“…Traditionally, the high work function metal palladium (Pd) has been used as the most popular contact material to the valence band of various nanostructures, including nanotubes, graphene, and organics [7] [8] [9] [10]. However Pd alone has proven insufficient as a hole contact for TMDC devices.…”

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confidence: 99%

“…This observation can be attributed to the sensitivity of the MoOx work function to ambient gas exposure [16]. This behavior is similar to elemental metal contacts to devices, which also show barrier height modulation due to gas exposure, and can be remedied by encapsulating the device [7] [9].…”

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confidence: 99%

MoS₂ P-type Transistors and Diodes Enabled by High Work Function MoO_x Contacts

et al. 2014

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Abstract-The development of low-resistance source/drain contacts to transition metal dichalcogenides (TMDCs) is crucial for the realization of high-performance logic components. In particular, efficient hole contacts are required for the fabrication of p-type transistors with MoS2, a model TMDC. Previous studies have shown that the Fermi level of elemental metals is pinned close to the conduction band of MoS2, thus resulting in large Schottky barrier heights for holes with limited hole injection from the contacts. Here, we show that substoichiometric molybdenum trioxide (MoOx, x<3), a high workfunction material, acts as an efficient hole injection layer to MoS2 and WSe2. In particular, we demonstrate MoS2 p-type field-effect transistors and diodes by using MoOx contacts. We also show drastic on-current improvement for p-type WSe2 FETs with MoOx contacts over devices made with Pd contacts, which is the prototypical metal used for hole

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“…We use Pd as contact material because it introduces little or no barrier at the nanotube-metal contact 12,13 . In a subsequent electron beam lithography step we 'write' the gate structures.…”

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Excited State Spectroscopy in Carbon Nanotube Double Quantum Dots

et al. 2006

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We report on low temperature measurements in a fully tunable carbon nanotube double quantum dot. A new fabrication technique has been used for the top-gates in order to avoid covering the whole nanotube with an oxide layer as in previous experiments. The top-gates allow us to form single dots, control the coupling between them and we observe four-fold shell filling. We perform inelastic transport spectroscopy via the excited states in the double quantum dot, a necessary step towards the implementation of new microwave-based experiments.Electron spins in double quantum dots (DQDs) are one of the leading systems for fundamental studies of elementary solid-state qubits 1 . Recent progress has been based on DQDs in 2-dimensional electron gases in GaAs semiconductor heterostructures 2,3 . However, the presence of non-zero nuclear spins

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Ballistic carbon nanotube field-effect transistors

Cited by 2,929 publications

References 27 publications

Single Carbon Nanotube Transistor at GHz Frequency

Single Carbon Nanotube Transistor at GHz Frequency

MoS₂ P-type Transistors and Diodes Enabled by High Work Function MoO_x Contacts

Excited State Spectroscopy in Carbon Nanotube Double Quantum Dots

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Ballistic carbon nanotube field-effect transistors

Cited by 2,929 publications

References 27 publications

Single Carbon Nanotube Transistor at GHz Frequency

Single Carbon Nanotube Transistor at GHz Frequency

MoS2 P-type Transistors and Diodes Enabled by High Work Function MoOx Contacts

Excited State Spectroscopy in Carbon Nanotube Double Quantum Dots

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Product

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MoS₂ P-type Transistors and Diodes Enabled by High Work Function MoO_x Contacts