Nanometer-Scale Resolution of Strain and Interdiffusion in Self-Assembled<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>InAs</mml:mi><mml:mi>/</mml:mi><mml:mi>GaAs</mml:mi></mml:math>Quantum Dots

Kegel, I.; Metzger, T. H.; Lorke, Axel; Peisl, J.; Stangl, J.; Bauer, G.; García, J. M.; Petroff, P. M.

doi:10.1103/physrevlett.85.1694

Cited by 210 publications

(145 citation statements)

References 23 publications

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“…This behavior is qualitatively predicted from our simulation 18 which shows that the OAM vector of the plike orbital state tends to be tilted toward the z-axis so does the g max direction as V sg is made positive. When the electron wavefunction shifts to the bottom of the QD the |g| value may become small, because Ga atoms are diffused from the GaAs substrate into the QD near the substrate 22,23 . Finally, we estimate the possible Rabi frequency of electron spin by means of g-TMR from the obtained results.…”

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confidence: 99%

Electrically tunable three-dimensionalg-factor anisotropy in single InAs self-assembled quantum dots

et al. 2013

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Three-dimensional anisotropy of the Landé g-factor and its electrical modulation are studied for single uncapped InAs self-assembled quantum dots (QDs). The g-factor is evaluated from measurement of inelastic cotunneling via Zeeman substates in the QD for various magnetic field directions. We find that the value and anisotropy of the g-factor depends on the type of orbital state which arises from the three-dimensional confinement anisotropy of the QD potential. Furthermore, the g-factor and its anisotropy are electrically tuned by a side-gate which modulates the confining potential.The Landé g-factor, the magnetic response of spin, is a physical constant reflecting the spin-orbit interaction (SOI) and the quantum confinement effect in semiconductor nanostructures, since it is determined by coupling between orbital and spin angular momentum 1 . In lowdimensional systems, the confining potential has large asymmetry resulting in an anisotropic g-factor. Therefore, the g-factor anisotropy can be electrically modulated by gating the quantum dot (QD) confining potential. This may be exploited for coherent manipulation of electron spins through g-tensor modulation resonance (g-TMR) which was previously studied for a quantum well 2 . For single electron spins, self-assembled QDs (SAQDs) and nanowire quantum dots (NWQDs) made out of narrow gap semiconductors such as InAs, InP and InSb are relevant for the study of g-factor anisotropy 3-6 , because they have quite large negative values of g-factor for electrons due to the strong SOI. In particular for InAs QDs we previously demonstrated that both the SOI effect and the orbital states are influenced by three-dimensional (3D) electrostatic potential 7,8 .Among SAQD systems InAs SAQDs are the most extensively studied in crystal growth as well as optical and electrical characterization. The InAs SAQDs in our study are uncapped or unstrained so that the QD size is relatively large, laterally 100 nm wide and vertically 30 nm high. The QD shape is anisotropic with the confinement strong in the out-of-plane direction and weak in the in-plane direction, leading to g-factor anisotropy 7 . Furthermore, the in-plane confinement is so weak that the confinement potential and the confined electron wavefunction can be modulated by means of electrical gating. A local or anisotropic gating has been applied to InAs SAQDs 8-10 and NWQDs 11 to modulate in-situ QD-lead tunneling coupling, and angular anisotropy of SOI energy and g-factor. In our previous study 10 of the electrical tuning of g-factor we identified tunability of the g-tensor only in a two-dimensional (2D) plane and assumed that the QD could be approximated as a disk-like 2D harmonic potential as if often done 12,13 . Studies of the anisotropy of the SOI have however shown that a 3D confinement, arising from the QD shape as well as the metal electrodes asymmetrically contacted to the QD, may be more realistic 8 . Such a 3D confinement leads to arbitral direction of orbital angular momentum (OAM) and therefore arbitral g-factor an...

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confidence: 99%

Electrically tunable three-dimensionalg-factor anisotropy in single InAs self-assembled quantum dots

et al. 2013

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“…Precise knowledge of these parameters, [1][2][3][4][5][6][7] on which optical and electrical properties depend, are of major interest. InAs SQDs in a GaAs matrix, grown by molecular beam epitaxy ͑MBE͒ in the Stranski-Krastanov growth mode, are of particular interest.…”

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confidence: 99%

Determination of the shape and indium distribution of low-growth-rate InAs quantum dots by cross-sectional scanning tunneling microscopy

Bruls

Vugs

Koenraad

et al. 2002

Applied Physics Letters

207

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We present a cross-sectional scanning-tunneling microscopy investigation of the shape, size, and composition of InAs quantum dots in a GaAs matrix, grown by molecular beam epitaxy at low growth rate. From the dimensional analysis we conclude that the investigated quantum dots have an average height of 5 nm, a square base of 18 nm oriented along ͓010͔ and ͓100͔ and the shape of a truncated pyramid. From outward relaxation and lattice constant profiles we conclude that the dots consist of an InGaAs alloy and that the indium concentration increases linearly in the growth direction. Our results justify the predictions obtained from previous photocurrent measurements on similar structures and the used theoretical model.

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“…Our results indicate that the same mechanism has worked for our InAlAs QDs. We note here, the interdiffusion of In-Ga which increases with temperature can be present in our growth as in InAs on GaAs [15,16]. As shown in Fig.…”

Section: Methodsmentioning

confidence: 65%

Effects of growth conditions on the size and density of self-assembled InAlAs/AlGaAs quantum dots grown on GaAs by molecular beam epitaxy

Izumi

Koyama

et al. 2011

Journal of Crystal Growth

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The effects of growth conditions on the size and density of self-assembled InAlAs/AlGaAs quantum dots (QDs) grown on GaAs by molecular beam epitaxy (MBE) were studied, with an emphasis on their use for single QD spectroscopy. The effects of substrate temperature and growth rate on the density and size were found to be quite similar to those of InAs QDs on GaAs.The effect of coverage, however, was different. Although the density was relatively high as compared to that of InAs QDs, it was reduced to 1 × 10 10 cm -2 under an optimized condition. This density is compatible with single QD spectroscopy with the help of a certain nanofabrication technique for areal restriction.

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Nanometer-Scale Resolution of Strain and Interdiffusion in Self-AssembledInAs/GaAsQuantum Dots

Cited by 210 publications

References 23 publications

Electrically tunable three-dimensionalg-factor anisotropy in single InAs self-assembled quantum dots

Electrically tunable three-dimensionalg-factor anisotropy in single InAs self-assembled quantum dots

Determination of the shape and indium distribution of low-growth-rate InAs quantum dots by cross-sectional scanning tunneling microscopy

Effects of growth conditions on the size and density of self-assembled InAlAs/AlGaAs quantum dots grown on GaAs by molecular beam epitaxy

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