Spectroscopy of electronic states in InSb quantum dots

Sikorski, Ch.; Merkt, U.

doi:10.1103/physrevlett.62.2164

Cited by 632 publications

(116 citation statements)

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“…Early far-infrared measurements on arrays of fewelectron dots, 6,7 and transport through single devices 8 were focused on the tunability of the electron number and, although transitions were observed, it was difficult to assign, for example, quantum numbers to these transitions. Later experiments using single-particle capacitance 9 and magneto-tunneling 10 spectroscopy focused on the evolution of the ground states as a function of magnetic field and were able to distinguish features consistent with the two-electron singlet-triplet transition.…”

Section: Introductionmentioning

confidence: 99%

Voltage-tunable singlet-triplet transition in lateral quantum dots

et al. 2002

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Section: Introductionmentioning

confidence: 99%

Voltage-tunable singlet-triplet transition in lateral quantum dots

et al. 2002

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“…This behavior is actually very often observed in experiments on quantum dots which are prepared from semiconductor heterostructures. [2,3] The reason being the electrostatic environment causing the external potential to have a nearly perfect parabolic shape. In other experiments, in particular on etched quantum dots with a larger number of electrons and a more hard-wall type of external potential, one observes additional sets of modes at higher frequencies (see for example Ref.4).…”

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confidence: 99%

Far-infrared excitations below the Kohn mode: Internal motion in a quantum dot

et al. 2001

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We have investigated the far-infrared response of quantum dots in modulation doped GaAs heterostructures. We observe novel modes at frequencies below the center-of-mass Kohn mode. Comparison with Hartree-RPA calculations show that these modes arise from the flattened potential in our field-effect confined quantum dots. They reflect pronounced relative motion of the charge density with respect to the center-of-mass.PACS numbers: 71.45. Gm,78.55.Cr, According to the generalized Kohn's theorem the farinfrared (FIR) response of a quantum dot with parabolic external potential in a magnetic field B consists, independent of the number of electrons in the quantum dot, of only two modes with dispersion:[1]Here Ω 0 describes the external potential, ω c = eB/m * is the cyclotron frequency, m * the effective mass. One mode, ω + , increases with increasing magnetic field and approaches the cyclotron frequency ω c , the other mode, ω − , decreases in frequency with decreasing magnetic field. Both modes represent rigid center-of-mass motion of all electrons in the dot. This behavior is actually very often observed in experiments on quantum dots which are prepared from semiconductor heterostructures. [2,3] The reason being the electrostatic environment causing the external potential to have a nearly perfect parabolic shape. In other experiments, in particular on etched quantum dots with a larger number of electrons and a more hard-wall type of external potential, one observes additional sets of modes at higher frequencies (see for example Ref.4). Such a mode spectrum can be calculated using a mean field approach and random phase approximation (RPA).[5] They can be visualized in terms of 'confined' plasmon modes, for example in the model of Fetter [6] (See also below for details). We have performed experiments on field-effectconfined quantum dots in AlGaAs/GaAs-heterostructures. We find in FIR experiments additional modes below the high-frequency Kohn mode, ω + , which are, however, definitely higher than ω c . The cyclotron resonance itself is not observed for these isolated dots. We compare our experiments with self-consistent Hartree calculations. From this comparison we find that the new modes arise from the flattened external potential in our field-effect-induced quantum-dot array. Our calculation shows that this new mode represents a dipole active charge-density oscillation involving strong relative motion of the electrons with respect to the center-of-mass.Quantum-dot arrays were prepared from modulationdoped Al 0.33 Ga 0.67 Al-GaAs heterostructures with a heterostructure interface-to-surface distance of 55 nm. A Si-δ doped layer was grown 300 nm underneath the AlGaAsGaAs interface and served as a backgate to charge the quantum dots. The sample design is sketched in the inset of Fig. 1. The electron density and mobility at 1.8 K were N S = 3.8 · 10 11 cm −2 and µ = 300 000 cm 2 /Vs, respectively. A photoresist-dot array was prepared by holographic lithography onto the sample surface with a period of a = 330 nm, the diamet...

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“…The change in refractive index is given by [25][26][27]29 n(ω) n r = n (1) (ω) n r + n (3) (ω) n r (9) with the linear n (1) n r and the third-order non linear n (3) n r refractive index changes given by n (1) …”

Section: -3mentioning

confidence: 99%

Linear and nonlinear intraband optical properties of ZnO quantum dots embedded in SiO2 matrix

2012

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In this work we investigate some optical properties of semiconductor ZnO spherical quantum dot embedded in an amorphous SiO2 dielectric matrix. Using the framework of effective mass approximation, we have studied intraband S-P, and P-D transitions in a singly charged spherical ZnO quantum dot. The optical properties are investigated in terms of the linear and nonlinear photoabsorption coefficient, the change in refractive index, and the third order nonlinear susceptibility and oscillator strengths. Using the parabolic confinement potential of electron in the dot these parameters are studied with the variation of the dot size, and the energy and intensity of incident radiation. The photoionization cross sections are also obtained for the different dot radii from the initial ground state of the dot. It is found that dot size, confinement potential, and incident radiation intensity affects intraband optical properties of the dot significantly

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Spectroscopy of electronic states in InSb quantum dots

Cited by 632 publications

References 14 publications

Voltage-tunable singlet-triplet transition in lateral quantum dots

Voltage-tunable singlet-triplet transition in lateral quantum dots

Far-infrared excitations below the Kohn mode: Internal motion in a quantum dot

Linear and nonlinear intraband optical properties of ZnO quantum dots embedded in SiO2 matrix

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