Photoluminescence of a low-density two-dimensional hole gas in a GaAs quantum well: Observation of valence-band Landau levels

Glasberg, S.; Shtrikman, Hadas; Bar‐Joseph, I.

doi:10.1103/physrevb.63.201308

Cited by 22 publications

(12 citation statements)

References 14 publications

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“…Similarly reduced values of the bulk g ⊥ were measured from the optical spectrum of excitons (e.g., g ⊥ 2.5 in Ref. 11) and were related as well to light-hole heavy-hole mixing [12,25]. In this framework, the level dependence of g ⊥ is possibly due to the lower subbands having a stronger lateral confinement, as confirmed by finite bias measurements.…”

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confidence: 67%

Characterization of Spin-Orbit Interactions of GaAs Heavy Holes Using a Quantum Point Contact

et al. 2014

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We present transport experiments performed in high quality quantum point contacts embedded in a GaAs two-dimensional hole gas. The strong spin-orbit interaction results in peculiar transport phenomena, including the previously observed anisotropic Zeeman splitting and level-dependent effective g-factors. Here we find additional effects, namely the crossing and the anti-crossing of spinsplit levels depending on subband index and magnetic field direction. Our experimental observations are reconciled in an heavy hole effective spin-orbit Hamiltonian where cubic-and quadratic-inmomentum terms appear. The spin-orbit components, being of great importance for quantum computing applications, are characterized in terms of magnitude and spin structure. In the light of our results, we explain the level dependent effective g-factor in an in-plane field. Through a tilted magnetic field analysis, we show that the QPC out-of-plane g-factor saturates around the predicted 7.2 bulk value.Spin-orbit interaction (SOI) is a relativistic effect that couples the motion of an electron to its spin [1]. For two-dimensional electron gases in the conduction band of III-V materials, SOI originates from bulk inversion asymmetry (Dresselhaus SOI [2]) and structure inversion asymmetry (Rashba SOI [3]) and takes the form, with σ the Pauli matrices and k the in-plane wavevector [4]. For two-dimensional hole gases (2DHGs) in the valence band of GaAs the situation is very different. Because of the non-zero orbital angular momentum, bulk SOI, and confinement in growth direction, SOI for holes is expected to be more pronounced than for their electronic counterparts, mainly of Rashba type and cubic in k [5,6]. The relevance of an additional term, quadratic in k and proportional to the in-plane components of the applied magnetic field B, was recently proposed [7][8][9][10]. Such a term is unique for heavy holes and very useful for exploiting SOI for quantum computing applications [7]. In this manuscript we show how the cubic and quadratic terms present in the bulk Hamiltonian can be separately addressed in the magnetoconductance of a quantum point contact (QPC) embedded in a 2DHG. Furthermore, our results offer a better understanding of the physics of ptype QPCs in terms of level dependent in-plane and outof-plane g-factors (g and g ⊥ respectively) and allow us to measure the bulk g ⊥ . The latter is particularly interesting, since the bulk g-factor anisotropy of p-type GaAs [11-13] makes it impossible to directly measure g ⊥ with conventional transport techniques [14]. Theoretical predictions for a [001]-growth 2DHG estimate g = 0 and g ⊥ = 7.2 [5,15]. It was argued [16] that in a QPC, in the limit of high subband index n, g ⊥ should approach the bulk value. So far, despite the tendency of g ⊥ to increase with n, this prediction was not experimentally confirmed.The experiment was performed using a carbon doped GaAs 2DHG grown along the [001] direction. A strong Rashba SOI is expected here due to the asymmetry of the confinement potential. A complete ...

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confidence: 67%

Characterization of Spin-Orbit Interactions of GaAs Heavy Holes Using a Quantum Point Contact

et al. 2014

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“…These lines labeled SU-X + and SU-A w X + have already been understood as shake-up replicas of free and acceptor-bound trions. 23,36,37 Let us note that a shake-up process couples recombination of a given complex with a cyclotron excitation of an additional free carrier in the surrounding gas, which in effect lowers the emission energy (compared to the "unshaken" transition) by a cyclotron energy. In our spectra, comparison of the energy-field dependence of the main and shake-up lines yield the slope difference of 0.3 meV/T corresponding to the hole effective mass m * h = 0.38 m e , matching the value known from the cyclotron resonance experiments.…”

Section: Resultsmentioning

confidence: 99%

“…35 Again, for the lack of precise quantitative predictions, unambiguous identification of these transitions in real PL spectra is problematic. Hence, while demonstration of many anticipated transitions and the underlying effects has been reported (e.g., electron and hole shake-up 36,37 ), some rather fundamental questions of relative stability of complexes or intensity of lines still remain controversial.…”

Section: Introductionmentioning

confidence: 99%

Optically induced charge conversion of coexistent free and bound excitonic complexes in two-beam magnetophotoluminescence of two-dimensional quantum structures

et al. 2012

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We report on extensive polarization-resolved photoluminescence (PL) studies of a variety of excitonic complexes formed in high-quality symmetric GaAs quantum wells containing a high-mobility two-dimensional (2D) hole gas in a broad range of magnetic fields from 0 to 23 T and under two-beam illumination, allowing for dynamical control of the hole concentration beyond the point of conversion from pto n-type structures. We have demonstrated charge conversion between positive and negative complexes bound to acceptors in the well, differing from the charge conversion of free trions due to charge reflection symmetry breaking by a fixed impurity, leaving a qualitative trace (exchange splitting) in the PL spectrum. The effect of switching between the electron and hole gases (in the same well) on different emission lines has also allowed us to distinguish the (direct and cyclotron-satellite) emission lines from positive trions moving almost freely in the quantum well and bound to nearby ionized acceptors in the barrier, thus demonstrating their coexistence in high-quality structures.

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“…For the core–multishell NWs, we observe additional emission lines at energies higher than the band gap of GaAs in the range 1.520–1.528 eV. This emission energy is typical for a GaAs quantum well (QW) of width 15–20 nm , suggesting a quantum confinement of the carriers in the core. To distinguish this high energy emission from the emission in other spectral regions we refer to it a “2D like” in the rest of the paper.…”

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confidence: 84%

Unintentional High-Density p-Type Modulation Doping of a GaAs/AlAs Core–Multishell Nanowire

et al. 2014

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Achieving significant doping in GaAs/AlAs core/shell nanowires (NWs) is of considerable technological importance but remains a challenge due to the amphoteric behavior of the dopant atoms. Here we show that placing a narrow GaAs quantum well in the AlAs shell effectively getters residual carbon acceptors leading to an unintentional p-type doping. Magneto-optical studies of such a GaAs/AlAs core-multishell NW reveal quantum confined emission. Theoretical calculations of NW electronic structure confirm quantum confinement of carriers at the core/shell interface due to the presence of ionized carbon acceptors in the 1 nm GaAs layer in the shell. Microphotoluminescence in high magnetic field shows a clear signature of avoided crossings of the n = 0 Landau level emission line with the n = 2 Landau level TO phonon replica. The coupling is caused by the resonant hole-phonon interaction, which points to a large two-dimensional hole density in the structure.

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Photoluminescence of a low-density two-dimensional hole gas in a GaAs quantum well: Observation of valence-band Landau levels

Cited by 22 publications

References 14 publications

Characterization of Spin-Orbit Interactions of GaAs Heavy Holes Using a Quantum Point Contact

Characterization of Spin-Orbit Interactions of GaAs Heavy Holes Using a Quantum Point Contact

Optically induced charge conversion of coexistent free and bound excitonic complexes in two-beam magnetophotoluminescence of two-dimensional quantum structures

Unintentional High-Density p-Type Modulation Doping of a GaAs/AlAs Core–Multishell Nanowire

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