Hole levels in InAs self-assembled quantum dots

Blokland, J.H.; Wijnen, Frans J. P.; Christianen, P.C.M.; Zeitler, U.; Maan, J.C.; Kailuweit, P.; Reuter, D.; Wieck, A. D.

doi:10.1103/physrevb.75.233305

Cited by 17 publications

(21 citation statements)

References 29 publications

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“…Here we present X-STM measurements on p-type InAs QDs, which are physically very relevant to understand fewparticle effects in quantum confined systems. [17][18][19] We find an unprecedented ellipsoidal shape with a large indium gradient in both vertical and horizontal directions. This result can be used as input for realistic models to better understand the charging characteristics and optical properties of semiconductor QDs.…”

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confidence: 76%

Ellipsoidal InAs quantum dots observed by cross-sectional scanning tunneling microscopy

Blokland¹,

Bozkurt²,

Ulloa³

et al. 2009

Applied Physics Letters

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confidence: 76%

Ellipsoidal InAs quantum dots observed by cross-sectional scanning tunneling microscopy

Blokland¹,

Bozkurt²,

Ulloa³

et al. 2009

Applied Physics Letters

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“…Figures 2(b) and (c) show the spin lifetime dependence on the vertical confinement in QDs with moderately strong and weak lateral confinement, respectively. These confinement strengths roughly correspond to self-assembled (panel (b)) [46,47] and electrostatic (panel (c)) [48] QDs. As can be seen in figure 2(b), electrons and holes have opposite behaviors.…”

Section: Geometry and Spin Splitting Dependencementioning

confidence: 94%

Spin–orbit-induced hole spin relaxation in InAs and GaAs quantum dots

2013

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We study the effect of valence band spin-orbit interactions (SOI) on the acoustic phonon-assisted spin relaxation of holes confined in quantum dots (QDs). Heavy hole-light hole (hh-lh) mixing and all the spin-orbit terms arising from zinc-blende bulk inversion asymmetry (BIA) are considered on equal footing in a fully three-dimensional Hamiltonian. We show that hh-lh mixing and BIA have comparable contributions to the hole spin relaxation in self-assembled QDs, but BIA becomes dominant in gated QDs. Simultaneously accounting for both mechanisms is necessary for quantitatively correct results in quasi-two-dimensional QDs. The dependence of the hole spin relaxation on the QD geometry and spin splitting energy is drastically different from that of electrons, with a non-monotonic behavior which results from the interplay between SOI terms. Our results reconcile contradictory predictions of previous theoretical works and are consistent with experiments. For a qualitative understanding of the geometry dependence of 1/T h 1 , we rewrite the hole states, equation (14), as | h m = J z c m J z |φ m J z |3/2, J z , where |φ m J z = r c m J z ,r |r is the envelope function associated with the periodic Bloch function |3/2, J z . If we restrict to the diagonal components of H h-ph , the matrix element determining the relaxation rate becomes

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“…-All computations were carried out for the InAs/GaAs quantum dot with parameters γ 1 = 11.01, γ 2 = 4.18, γ 3 = 4.84, κ = 1.2 and the dielectric constant, ε = 12.4 [28]. The height of the dot is taken as L = 4.5 nm and the in-plane confinement energȳ hω 0 = 20 meV which seems to be very reasonable [18,29].…”

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confidence: 99%

“…1(b)], where the energy of the state F z = 5/2 increases with increasing magnetic field. This difference in the magnetic behavior is due to particular assumptions in [18] that are employed to derive the hole energy from the experimental data. However, what is crucial here is the separation between the two curves that is very similar in both cases.…”

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Enhanced Rashba effect for hole states in a quantum dot

Manaselyan

Chakraborty

2009

Europhys. Lett.

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Abstract. -The effect of Rashba spin-orbit (SO) interaction on the hole states in a quantum dot is studied in the presence of an external magnetic field. We demonstrate here that the Rashba SO coupling has a profound effect on the energy spectrum of the holes revealing level repulsions between the states with the same total momentum. We also show that the resulting spin-orbit gap is much larger than the corresponding one for the electron energy levels in a quantum dot. Inter-hole interactions only marginally reduce the spin-orbit gap. This enhanced Rashba effect would manifest itself in the tuneling current which depends on the spin-orbit coupling strength.Introduction. -Semiconductor quantum dots are the nanoscale zero-dimensional systems with discrete energy levels, much like in atoms (and hence the popular name, artificial atoms [1]). They have one great advantage that their shape and the number of electrons in those systems can be controlled externally and as a result, they have been the subject of intense research in recent years. They are particularly promising as components of futuristic devices for quantum information processing [2] and for coherent spin transport [3]. The spin states of these systems are ideal for applications because of their relative insensitivity to electrical noise in a device environment [4]. One proposed mechanism for coherent spin manipulation in quantum nanostructures is via the Rashba spin-orbit (SO) coupling [5,6]. The SO interaction can arise in a quantum dot due to confinement and lack of inversion symmetry of the nanostructure which creates a local electric field perpendicular to the electron plane [7,8]. The SO coupling strength can be varied by changing the asymmetry of the quantum structure with an external electric field. The magnetic field effects on the properties of lowdimensional systems, such as quantum wells and quantum dots with the Rashba interaction has been reported in experiments [9] and theory [10]. In our work on Rashba effects in electron dots [11], we found multiple level crossings and level repulsions that resulted from the interplay between the Zeeman and the SO couplings. Level anticrossings observed in quantum nanostructures have been attributed to the presence of SO coupling in those systems [12]. However, studies of the Rashba effect on quan-

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Hole levels in InAs self-assembled quantum dots

Cited by 17 publications

References 29 publications

Ellipsoidal InAs quantum dots observed by cross-sectional scanning tunneling microscopy

Ellipsoidal InAs quantum dots observed by cross-sectional scanning tunneling microscopy

Spin–orbit-induced hole spin relaxation in InAs and GaAs quantum dots

Enhanced Rashba effect for hole states in a quantum dot

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