Tunneling Spectroscopy of InAs Wetting Layers   and Self-Assembled Quantum Dots:    Resonant Tunneling through Two- and Zero-Dimensional Electronic States

Suzuki, Toshimitsu; Nomoto, Kazumasa; Taira, K.; Hase, I.

doi:10.1143/jjap.36.1917

Cited by 45 publications

(16 citation statements)

References 17 publications

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“…Despite the large number of quantum dots in our sample (10 6 − 10 7 for a 100µm diameter mesa), we observed only a small number of resonant peaks over the bias range (∼ 200 mV ) close to the threshold for current flow. This behaviour has been reported in earlier studies [4,6,[8][9][10][11][12] and, although not fully understood, is probably related to the limited number of conducting channels in the emitter that can transmit electrons from the doping layer to the quantum dots at low bias. There is no reason to believe that the dots studied are atypical of the distribution as a whole.…”

Section: Methodssupporting

confidence: 54%

Spatial mapping of the electron eigenfunctions in InAs self-assembled quantum dots by magnetotunnelling

et al. 2002

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Section: Methodssupporting

confidence: 54%

Spatial mapping of the electron eigenfunctions in InAs self-assembled quantum dots by magnetotunnelling

et al. 2002

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“…In the earlier studies of resonant electron tunneling, samples with ensembles of InAs QDs were investigated at very low temperatures [9][10][11][12][13]. For instance, resonant tunneling diodes (RTD) of 30-100 mm in diameter, which contain 10 6 -10 7 QDs embedded in barrier layers were studied and found to show a current peak caused by resonant tunneling through a single QD.…”

Section: Introductionmentioning

confidence: 99%

Resonant tunneling of electrons through a single self-assembled InAs quantum dot probed via a novel overlayed quantum dot electrode

Kamiya

Tanaka

Tada

et al. 2005

Journal of Crystal Growth

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“…8,9,17,18 We attribute this to the fact that the energy levels of the QD ground states lie below the chemical potential in the emitter at all biases so energy-conserving tunneling transitions through the dots are not allowed.…”

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confidence: 99%

Excited states of ring-shaped (InGa)As quantum dots in aGaAs∕(AlGa)Asquantum well

et al. 2005

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By studying the resonant tunneling of electrons through self-assembled ring-shaped ͑InGa͒As quantum dots embedded in the quantum well of an ͑AlGa͒As/ GaAs/ ͑AlGa͒As heterostructure, we find evidence for the existence of excited states of the quantum dots which exhibit a 2p z -like character along the growth direction z. The states are investigated by magnetotunneling spectroscopy with magnetic fields applied parallel and perpendicular to z. DOI: 10.1103/PhysRevB.72.085309 PACS number͑s͒: 73.23.Ϫb, 73.63.Kv, 73.40.Gk In self-assembled semiconductor quantum dots ͑QDs͒, carriers are confined in all three spatial dimensions. This leads to a spectrum of discrete energy levels, similar to that of atoms. [1][2][3][4][5][6][7] The analogy with atoms is strengthened by the observation of excitonic and electronic states with s-, p-, and d-like character, all of which have been observed in optical 6 and tunneling 8,9 spectroscopy studies. In addition, optical pumping experiments have provided evidence for shell-like filling of the electronic orbitals. 6 However, in contrast to a real atom, a QD has a highly anisotropic confining potential, since its dimensions in the plane of growth ͑the wetting layer plane x-y͒ are typically an order of magnitude larger than that along the growth direction ͑z͒. Hence spectroscopic investigations have been restricted mainly to states for which the excitations are confined to the x-y plane.In this paper, we study the electronic properties of QDs with an unusual ring-shape morphology, which can be generated under special growth conditions. We report experimental evidence for the presence of excited QD states with a 2p z -like character. States with 2p z character have been observed previously for Si donors in a GaAs QW.10 For this study we use resonant tunneling heterostructure diodes in which a single layer of self-assembled ͑InGa͒As quantum dots is embedded in an ͑AlGa͒As/ GaAs/ ͑AlGa͒As quantum well. The 2p z -like quasibound states are revealed by the presence of additional resonant peaks in the tunnel current. By combining photoluminescence and magnetotunneling spectroscopy with magnetic field B applied along z and in the x-y plane, we show that these resonances correspond to electron tunneling into 2p z -like states with binding energies in the range 5 -30 meV below the edge of the continuum of the first excited two-dimensional ͑2D͒ subband of the GaAs QW.Despite the ring-shape structure of the dots, we find no evidence in our tunneling data for states showing AharonovBohm character.Our device is a GaAs/ Al 0.4 Ga 0.6 As double barrier electron resonant tunneling diode ͑RTD͒ grown by molecular beam epitaxy ͑MBE͒ on a ͑100͒-oriented n + GaAs substrate. The conduction band profile of the device and the QD energy levels are shown schematically in Fig. 1͑a͒. Two 8-nm-thick Al 0.4 Ga 0.6 As tunnel barriers define a 10-nm-thick GaAs QW, which contains a layer of ͑InGa͒As QDs. Undoped GaAs spacer layers of width 50 nm separate the Al 0.4 Ga 0.6 As barriers from lightly n-doped ͑n =2ϫ 10 1...

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Tunneling Spectroscopy of InAs Wetting Layers and Self-Assembled Quantum Dots: Resonant Tunneling through Two- and Zero-Dimensional Electronic States

Cited by 45 publications

References 17 publications

Spatial mapping of the electron eigenfunctions in InAs self-assembled quantum dots by magnetotunnelling

Spatial mapping of the electron eigenfunctions in InAs self-assembled quantum dots by magnetotunnelling

Resonant tunneling of electrons through a single self-assembled InAs quantum dot probed via a novel overlayed quantum dot electrode

Excited states of ring-shaped (InGa)As quantum dots in aGaAs∕(AlGa)Asquantum well

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