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Tewordt, M.; Martín‐Moreno, Luis; Law, V. J.; Kelly, M. J.; Newbury, R.; Pepper, M.; Ritchie, D. A.; Frost, J. E. F.; Jones, G. A. C.

doi:10.1103/physrevb.46.3948

Cited by 48 publications

(16 citation statements)

References 26 publications

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“…It is noted that the high Fermi energy of the gold contacts (∼2 eV) as compared to the low energies of semiconductor quantum dot systems (<100 meV) precludes the observation of negative differential resistance in the present system, 23 which is often seen in semiconductor systems. 1–7 A control experiment with unevaporated THF solvent alone (that is, without the benzene‐1, 4‐dithiolate) exhibited a resistance of 1–2 Gohm (linear up to 10V independent of electrode spacing, implying ionic conduction through the solvent. When the solvent was evaporated, regular vacuum tunneling with a much higher resistance was observed, 19 with exponential dependence of the current with applied voltage implying the absence of deleterious effects on the MCB due to the solvent.…”

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confidence: 99%

The Electrical Measurement of Molecular Junctions

Reed

Zhou

Deshpande

et al. 1998

Annals of the New York Academy of Sciences

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We present the investigation of the electrical transport of metal/(organic molecule or monolayer)/metal junctions. Utilizing a novel mechanically controllable break junction to form a statically stable system, we have self-assembled molecules of benzene-1,4-dithiol onto two facing gold electrodes allowing for direct observation of charge transport through the molecules. Current-voltage I(V) measurements provides a quantitative measure of the conductance of a junction containing a single molecule. We have also created a technique to form well-defined, stable, and reproducible metallic contacts to a self-assembled monolayer of 4-thioacetylbiphenyl with nanoscale area. Electronic transport measurements show a prominent rectifying behavior arising from the asymmetry of the molecular heterostructure. Variable-temperature measurements reveal the dominant transport mechanisms, such as thermionic emission for the Ti-organic system. These techniques demonstrate the capability of electrically characterizing and engineering conductive molecular systems for future potential device applications.The measurement of charge transport in single organic molecules, and the determination of their conductance, is a long-sought goal. Such measurements are experimentally challenging and intriguing since one can test the validity of transport approximations at the molecular level. A conceptually simple configuration would be to connect a single molecule between metallic contacts. Such a metal-moleculemetal configuration would present the molecular embodiment of a system analogous to a quantum dot, 1-9 with the potential barriers of the semiconductor system replaced by any existing contact barrier of the molecule/metal interface. Previous measurements on atomic and molecular systems have been done by scanning tunneling microscopes (STM), [10][11][12] and can yield conductivity information. [13][14][15] Experiments with an evaporated-metal-top contact/molecules/metallic-bottom-contact configuration, which has ten of thousands of parallel active molecules, have also been demonstrated. 16,17 One experiment on an organic system 18 reported evidence for Coulomb charging. We have performed measurements in the configuration of a single molecule between metallic contacts; specifically on benzene-1,4-dithiolate connected between stable proximal metallic gold contacts, at room temperature. This approach complements previous approaches by presenting statically stable contacts, and concurrently restricts the number of active molecule(s) to as few as one.

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confidence: 99%

The Electrical Measurement of Molecular Junctions

Reed

Zhou

Deshpande

et al. 1998

Annals of the New York Academy of Sciences

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“…On the other hand, intentional impurity profiles on semiconductor nanostructures can be used to monitor a great number of their physical properties. Resonant tunneling through shallow donor impurity states in double-barrier diodes has been extensively studied experimentally [4][5][6][7][8][9]. The donor impurities give rise to an additional resonant peak in the current-voltage characteristics at a voltage below that of the main resonance corresponding to tunneling of electrons from two-dimensional free-electronlike states into the two-dimensional subband of the quantum well.…”

Section: Introductionmentioning

confidence: 99%

Magnetotunneling in GaAs/AlxGa1-xAs Double Barrier Heterostructures with and without On-Center-Well Impurity Planes

Gutiérrez

Latgé

Porras‐Montenegro

2002

phys. stat. sol. (b)

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By means of the diagrammatic techniques for nonequilibrium processes proposed by Keldysh and adopting a simple one-band tight-binding Hamiltonian, we study the resonant tunneling in GaAs/ Al x Ga 1 À x As double-barrier heterostructures (DBH) in the presence of a magnetic field applied parallel to the current direction in this work. We have found that the number of Landau levels that contribute to the resonant tunneling diminishes with the magnetic field, all centered around the position of the resonance. Also, we have calculated the conductance versus bias voltage and we have found that the maxima and minima of the conductance move towards higher bias with the magnetic field in good agreement with experimental reports. We have considered the effects of isoelectronic impurity-planes localized at the well region on the J-V characteristics of the system and on the conductance versus voltage. The presence of the impurity-plane induces a shift to higher (lower) energies of the density of states, of the J-V characteristic curves and of the conductance versus voltage, corresponding to a repulsive (attractive) potential.

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“…Observations of resonant tunneling in ultrasmall resonant tunneling diodes ͑RTDs͒ have shown fine structure in the current-voltage ͑I-V͒ characteristics superimposed on the normal resonant tunneling curves at very low temperatures. Different mechanisms such as the surfacedepletion structure from the sidewalls, 2-13 single impurity states [14][15][16] and potential fluctuations 16,17 have been proposed as the origin of the quantization that produces the observed fine structure. Additional effects such as subband-mixing coupling 8,9,[18][19][20] and single-electron charging [5][6][7][11][12][13]21,22 may also contribute to the I-V characteristics.…”

Section: Introductionmentioning

confidence: 99%

“…9,15,17,[28][29][30][31][32] The present authors 33 have proposed the application of intense magnetic fields parallel to the current axis in order to determine whether or not the fine structure observed by Reed et al 2 originates from subband mixing at the interfaces due to sidewall depletion.…”

Section: Introductionmentioning

confidence: 99%

Subband mixing in resonant magnetotunneling through double-barrier semiconductor nanostructures

Farinas

Marques

Studart

1996

Journal of Applied Physics

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We investigate subband mixing in the magnetotunneling of an electron through a double-barrier quantum dot. The fine structure in the current-voltage characteristics, observed in a device formed by a quantum-dot sandwiched by two quantum-wire contacts, is studied as a function of a magnetic field applied along the direction of the tunneling current. The increase of the magnetic field in this one-dimensional-zero-dimensional-one-dimensional tunneling process leads to a transition from a low-field regime dominated by lateral confinement to a high-field regime dominated by magnetic confinement. The fine structure is shifted due to the magnetic field. The main result is that, as the magnetic field increases, the effect of the subband mixing at the interfaces becomes negligible and the fine structure tends to disappear at strong fields. We provide a straightforward interpretation for the mechanism underlying this transition and conjecture that it has the same origin as the one recently observed in a different device.

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Resonant tunneling in anAlxGa1−

Cited by 48 publications

References 26 publications

The Electrical Measurement of Molecular Junctions

The Electrical Measurement of Molecular Junctions

Magnetotunneling in GaAs/AlxGa1-xAs Double Barrier Heterostructures with and without On-Center-Well Impurity Planes

Subband mixing in resonant magnetotunneling through double-barrier semiconductor nanostructures

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