Resonant tunneling through the bound states of a single donor atom in a quantum well

Dellow, M. W.; Beton, Peter H.; Langerak, C.J.G.M.; Foster, T.J.; Main, P. C.; Eaves, L.; Henini, M.; Beaumont, S. P.; Wilkinson, C.D.W.

doi:10.1103/physrevlett.68.1754

Cited by 217 publications

(48 citation statements)

References 13 publications

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“…Such impurity states with an energy lower than the quantum well in between the barriers most likely stem from unintended donor atoms within the well. [11][12][13][14] The I-Vcurve is slightly asymmetric regarding both bias polarities. We attribute this to the different transmission coefficients of both tunneling barriers due to their differing growth thicknesses.…”

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confidence: 99%

Shot noise in resonant tunneling through a zero-dimensional state with a complex energy spectrum

et al. 2004

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We investigate the noise properties of a GaAs /Al x Ga 1Ϫx As resonant-tunneling structure at bias voltages where the current characteristic is determined by single electron tunneling. We discuss the suppression of the shot noise in the framework of a coupled two-state system. For large bias voltages we observe superPoissonian shot noise up to values of the Fano factor ␣Ϸ10. DOI: 10.1103/PhysRevB.69.113316 PACS number͑s͒: 73.63.Kv, 73.40.Gk, 72.70.ϩm Shot noise allows for a direct measurement of the correlation in a current of discrete charges. In the case of a totally uncorrelated current, one observes the so-called full or Poissonian shot noise. 1 The corresponding noise power S displays a linear dependence Sϭ2eI on the stationary current I as long as the applied bias voltage V SD is large compared to the thermal energy: eV SD ӷ2k B T. 2 Full current shot noise arises, e.g., in a single tunneling barrier, since the tunneling process of different electrons are independent of each other.However, if an additional source of negative correlation is introduced the noise amplitude was shown to be reduced. 3,4 For resonant tunneling through a double-barrier structure this is attributed to the dependency of successive tunneling events caused by the finite dwell time of the resonant state. 5,6 This suppression of the shot noise has also been observed for resonant tunneling through zero-dimensional systems. 7,8 For the opposite case of a positive correlation between individual tunneling events the noise power can even become super-Poissonian. 9,10 We report on noise measurements of a resonant-tunneling double-barrier structure. Under certain bias conditions the tunneling current through our sample flows through a single zero-dimensional state. 13,14 Therefore we are dealing with 3d-0d-3d tunneling in contrast to the above-mentioned experimental studies where the tunneling takes place through a two-dimensional subband (3d-2d-3d). 5,6 Our sample consists of a nearly symmetric double-barrier resonant-tunneling structure grown by molecular-beam epitaxy on a n ϩ -type GaAs substrate ͓see Fig. 1͑a͔͒. The heterostructure is formed by a 10-nm-wide GaAs quantum well sandwiched between two Al 0.3 Ga 0.7 As-tunneling barriers of 5 and 6 nm thickness. The contacts consist of 300-nm-thick GaAs layers doped with Si (4ϫ10 17 cm Ϫ3 ) and they are separated from the active region by a 7 nm thick undoped GaAs spacer layer. The geometrical diameter of the diode is 1 m.The current-voltage (I-V) characteristic is plotted in Fig. 1͑c͒. The upper inset shows the characteristic shape of the resonance due to tunneling through the two-dimensional subband at V SD ϭϮ130 mV. However, we concentrate our measurements on small bias voltages ͉V SD ͉р10 mV, where we find a pronounced current step ͑marked with ''X''͒. This feature indicates the presence of at least one single impurity in the nominally undoped GaAs, as depicted schematically in Fig. 1͑b͒. Such impurity states with an energy lower than the quantum well in between the barriers most like...

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Shot noise in resonant tunneling through a zero-dimensional state with a complex energy spectrum

et al. 2004

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“…Recently, we developed a technique to image the LDOS in heavily doped GaAs [7], which is based on resonant tunneling through impurity states [5,[8][9][10] in asymmetric double-barrier heterostructures. In agreement with theory [4,5], we found at low magnetic fields strong irregular LDOS fluctuations [7].…”

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Observation of the Local Structure of Landau Bands in a Disordered Conductor

et al. 1997

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“…11). It has been proposed that these are due to resonant tunnelling into the localized bound states of a small number of donor impurities in the nominally undoped QW [21]. We now consider what information the magnetotunnelling technique will provide in this situation [22].…”

Section: Resonant Tunnelling Of Holes In P-type Narrow-well Double-bamentioning

confidence: 99%

Physics of Resonant Tunnelling

Sheard

Fromhold

1992

Acta Phys. Pol. A

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A description is given of resonant tunnelling processes in double-barrier semiconductor heterostructures from the point of view of sequential theory. If a magnetic field is applied in the plane of the barrier interfaces, the energy and transverse momentum of the electrons injected into the quantum well through the emitter tunnel barrier can be varied independently by changing the applied voltage and magnetic field. This technique can be used to probe the energy and momentum spectrum of the subband states in a quantum well. In n-type wide-well structures, a detailed interpretation of niagneto-oscillations in the tunne1 current has been given in terms of semiclassical orbits of electrons in the well. In p-type structures with narrow wells, the dispersion curves of hole subbands, which are complicated by the strong mixing of light hole and heavy hole states, have been directly studied. Resonant tunnelling into the bound state of single donor atks in a quantum well has recently been observed. The magnetic field dependence of the tunnel current then gives a measure of the transverse momentum distribution and hence lateral extent of the donor wave function.

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Resonant tunneling through the bound states of a single donor atom in a quantum well

Cited by 217 publications

References 13 publications

Shot noise in resonant tunneling through a zero-dimensional state with a complex energy spectrum

Shot noise in resonant tunneling through a zero-dimensional state with a complex energy spectrum

Observation of the Local Structure of Landau Bands in a Disordered Conductor

Physics of Resonant Tunnelling

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