Direct measurement of the density of states of a two-dimensional electron gas

Smith, Thor L.; Goldberg, Bennett B.; Stiles, P. J.; Heiblum, M.

doi:10.1103/physrevb.32.2696

Cited by 259 publications

(140 citation statements)

References 18 publications

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“…The exit path therefore forms a resistive divider with the tunnel barrier, and the voltage drop across the tunnel barrier is thus not accurately known. A similar problem occurs when measuring the capacitance of MOSFETs at high values of perpendicular magnetic field, [14][15][16] and this difficulty has necessitated sophisticated capacitive techniques to measure such basic quantities as the density of states of 2DEGs. 17 We therefore design the insulating barrier in our samples to block D.C. transport over the range of D.C. biases V DC used in the experiment.…”

Section: Measuring Quasi-bound State Lifetimementioning

confidence: 99%

“…16,17 We probe tunneling in and out of the 2DEG in our samples using the complex, frequencydependent impedance of the device. This technique has been used previously to study energy gaps [18][19][20] and density of states 21 in 2DEG systems, as well as tunneling times and density of states in buried GaAs 22 and InAs 23,24 quantum dots.…”

Section: Measuring Quasi-bound State Lifetimementioning

confidence: 99%

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Scattering-assisted tunneling: Energy dependence, magnetic field dependence, and use as an external probe of two-dimensional transport

et al. 2010

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For more than three decades, research on tunneling through planar barriers has focused principally on processes that conserve momentum parallel to the barrier. Here we investigate transport in which scattering destroys lateral momentum conservation and greatly enhances the tunneling probability. We have measured its energy dependence using capacitance spectroscopy, and we show that for electrons confined in a quantum well, the scattering enhancement can be quenched in an applied magnetic field, enabling this mechanism to function as an external probe of the origin of the quantum Hall effect.

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Section: Measuring Quasi-bound State Lifetimementioning

confidence: 99%

Section: Measuring Quasi-bound State Lifetimementioning

confidence: 99%

Scattering-assisted tunneling: Energy dependence, magnetic field dependence, and use as an external probe of two-dimensional transport

et al. 2010

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“…At fixed temperature Fig.3 represents the depen- Then, upon decreasing of 2DEG density( i.e. µ → 0) the experimental data [21,22,23] exhibit diminish and, furthermore, the negative inverse compressibility compared to d 0 . Usually, this behavior is explained [22] in terms of conventional Hartree-Fock exchange omitted in our simple approach.…”

Section: ∆T = ∆αL0mentioning

confidence: 99%

“…It is of particular interest the 2DEG compressibility, K = dN dµ = − d 2 Ω dµ 2 , known to be a fundamental quantity generally more amenable to theoretical and experimental analysis. [21,22,23] For noninteracting 2DEG system Eq. (3) yields…”

Section: ∆T = ∆αL0mentioning

confidence: 99%

Thermal correction to resistivity in dilute 2D Si-based systems

Cheremisin

2005

Physica E: Low-dimensional Systems and Nanostructures

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We calculate the resistivity of 2D electron (hole) gas, taking into account the degeneracy and the thermal correction due to the combined Peltier and Seebeck effects. The resistivity is found to be universal function of temperature, expressed in units of h e 2 (kF l) −1 . The giant parallel magnetiresistivity found to result from the spin and, if exists, valley splitting of the energy spectrum. Our analysis of compressibility and thermopower points to thermodynamic nature of metal-insulator transition in 2D systems. PACS numbers: 73.40.Qv, 71.30+h, 73.20.Fz Recently, a great deal of interest has been focussed on the anomalous transport behavior of a wide variety of low-density 2D electron [1,2] and hole [3,4,5] systems. It has been found that, below some critical density, the cooling causes an increase in resistivity, whereas in the opposite high density case the resistivity decreases. Another unusual property of dilute 2D systems is their enormous response to parallel magnetic field. At low temperatures the magnetic field found to suppress the metallic behavior of 2D electron(hole) gas and result in strong increasing of resistivity upon enhancement of spin polarization degree [6,7]. At high temperatures the parallel magnetoresistivity starts to be unaffected by magnetic field when the temperature exceeds a value being of the order of Zeeman energy. A strong perpendicular magnetic field, if applied simultaneously with the parallel one, results in suppression of parallel magnetoresistivity [8]. Although numerous theories have been put forward to account for these effects, the origin of the above behavior is still the subject of a heated debate.The ohmic measurements known to be carried out at low current I → 0 in order to prevent heating. Usually, only the Joule heat is considered to be important. In contrast to the Joule heat, the Peltier and Thomson effects are linear in current. As shown in Refs. [9,10,11], the Peltier effect influences ohmic measurements and results in a correction to a measured resistance. When current is flowing, one of the sample contacts is heated, and the other cooled, because of the Peltier effect. The contact temperatures are different. The voltage drop across the circuit includes the Seebeck thermoelectromotive force, which is linear in current. Finally, there exists a thermal correction ∆ρ, to the ohmic resistivity, ρ, of the sample. For degenerate electrons, ∆ρ/ρ ∼ (kT /µ) 2 , where µ is the Fermi energy. Hence, the correction may be comparable with the ohmic resistance of a sample when kT ∼ µ.In the present paper, we report on a study of low-T transport in 2D electron(hole) gas, taking into account both the electron degeneracy and the Peltier-effectinduced correction to resistivity. [9,10]. The parallel magnetoresistivity found to originate from the spin and,if exists, valley splitting of 2D energy spectrum.Let us consider, for clarity, the (100) MOSFET 2DEG system. The electrons are assumed to occupy the first quantum-well subband with isotropic energy spectrum ε(k) =h 2 k 2 2m...

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“…In both, the DC potentials (−V fb ) display the same characteristic step of ∼h! c =2 associated with the Fermi level passing between the third and second Landau levels [6,8], but the accompanying AC signal amplitude di ers by up to ×10. Quantitatively, the smaller signals in the right panel in Fig.…”

mentioning

confidence: 99%

Single-electron states in the quantum Hall effect

Zhitenev¹,

Fulton²,

Yacoby³

et al. 2000

Physica E: Low-dimensional Systems and Nanostructures

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Spatially localized electronic states in a two-dimensional electron gas in the quantum Hall regime are imaged using a scanning single-electron-transistor probe. Two di erent regimes of localization are identiÿed depending on the strength of the built-in long-range density uctuations. In the smoother regions localized states merge into dielectric-like blobs a few m in extent. In the places with a stronger density gradient complex patterns occur which change markedly with an addition of a single electron. The simplest appearance of the latter is a ring collapsing toward the center as an electron is added to the area. ?

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Direct measurement of the density of states of a two-dimensional electron gas

Cited by 259 publications

References 18 publications

Scattering-assisted tunneling: Energy dependence, magnetic field dependence, and use as an external probe of two-dimensional transport

Scattering-assisted tunneling: Energy dependence, magnetic field dependence, and use as an external probe of two-dimensional transport

Thermal correction to resistivity in dilute 2D Si-based systems

Single-electron states in the quantum Hall effect

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