Enhancement of Rashba interaction in GaAs/AlGaAs quantum wells due to the incorporation of bismuth

Simmons, R. A.; Jin, S. R.; Sweeney, S. J.; Clowes, S. K.

doi:10.1063/1.4932122

Cited by 19 publications

(10 citation statements)

References 27 publications

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“…The increasing interest for gallium arsenic bismide alloys (GaAs1-xBix) calls for a high level of Bi incorporation in the samples, as the red-shift of the band-gap (88 meV/% Bi) and the related noteworthy properties depend directly upon that value [1][2][3][4][5][6][7]. Unfortunately, the quality of grown GaAs1-xBix crystals rapidly decays with the amount of Bi, imposing new and sometimes unconventional growth strategies to gain a higher incorporation of Bi in GaAs: low temperature of the substrate [8], variable flux of Bi and 1:1 As to Ga flux ratio for favoring the Bi incorporation [9].…”

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confidence: 99%

Reflectance anisotropy spectroscopy of strain-engineered GaAsBi alloys

Goletti

Fazi

Tisbi

et al. 2022

Applied Physics Letters

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In this paper we present results obtained by an optical technique, namely Reflectance Anisotropy Spectroscopy (RAS), applied to a series of GaAs1-xBix samples grown by Molecular Beam Epitaxy (MBE) under different strain conditions with increasing concentration of Bi, up to the higher value of about 7%. The epitaxial buffer layers for the growing GaAs1-xBix layer were prepared with either a compressive strain (as it is commonly done) or a tensile strain: the latter case has been proven to be a strategy that allows to obtain a better crystalline quality [E.

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confidence: 99%

Reflectance anisotropy spectroscopy of strain-engineered GaAsBi alloys

Goletti

Fazi

Tisbi

et al. 2022

Applied Physics Letters

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“…have shown theoretically that in modulation-doped quantum wells the Rashba term increases significantly in dilute bismide alloys when the bismuth fraction increases due to the respective increase and the decrease of spin-orbit split-off and band gap energies 57 . In GaAsBi, the Rashba term increases faster than the Dresselhaus one as the Bi content increases.…”

Section: Bismuth Content Dependence Of the Electron Spin Relaxation Tmentioning

confidence: 99%

Bismuth content dependence of the electron spin relaxation time in GaAsBi epilayers and quantum well structures

Azaizia¹,

Balocchi²,

Mazzucato³

et al. 2018

Semicond. Sci. Technol.

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Time-resolved optical orientation experiments have been performed in dilute bismidestructures. Bulk layers with bismuth fractions in the range 1-3.8% and quantum wells with bismuth fractions in the range 2.4-7% were investigated. A clear decrease of the electron spin relaxation time is evidenced in both cases when the bismuth content increases. These results can be well interpreted by the increased efficiency of the spin relaxation mechanisms due to the bismuth induced larger spin-orbit interaction in these alloys.The incorporation of small concentrations of bismuth (Bi) into GaAs yields a significant reduction of the band gap energy 0F 1 , 2 . As a consequence the dilute bismide alloys, GaAs 1−x Bi x , are interesting for potential optical telecommunication or photovoltaic applications 3,4 . As Bismuth is a heavy atom, dilute bismides are also characterized by a much larger spin-orbit interaction compared to GaAs 5 . Indeed, an increase of the valence band spin-orbit (SO) split-off energy Δ was clearly evidenced in GaAsBi with values reaching ~800 meV and above (i.e. twice the GaAs value) for a bismuth composition of about 10% 6 .This remarkable property has triggered massive efforts to improve alloy growth, as the condition Δ > could lead to a significant reduction of Auger or Inter Valence Band Absorption loss mechanisms in the NIR telecommunication range as suggested by Sweeney's group et al 7 , 8 . This system has also been proposed as a good candidate for spintronic applications by Fluegel et al. as the enhanced SO coupling in this material allows for a composition-dependent SO engineering and hence possible electron spin tuneability and manipulation 5 .For these reasons, the role of the SO interaction on the electron Landé g-factor in bulk GaAsBi was studied both theoretically and experimentally 9 , 10 . It was shown that the introduction of a Bi fraction of the order of 0.03 led to an increase of the g-factor by a factor of 3. Similar observations were made on the exciton g-factors in quantum wells in the low temperature range 11 .Besides, the elctrons spin relaxation time is a key parameter for spin manipulations as the spin memory should last longer than the manipulation time in order to make use of the electron spin as the information vector. Tong et al. predicted theoretically that the electron spin relaxation time in GaAsBi decreases drastically when the Bi content increases 12 . The experimental investigation of the electron spin relaxation rate in a bulk sample with a bismuth fraction of 2.2% confirmed these predictions 9 . The result was in good agreement with the characterization of the product . (where is the electron Landé factor) determined by Pursley et al. via Hanle effect measurements 13 . However, a measurement of the bismuth dependence of the electron spin relaxation time is still lacking although it is essential to assess the potential of dilute bismides for spintronic applications. In this work we have measured the electron spin dynamics by time-and polarization-resolved photoluminescen...

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“…Highly-mismatched III-V semiconductor alloys containing dilute concentrations of bismuth (Bi) have attracted significant attention in recent years 1 since their unique electronic properties open up a range of possibilities for practical applications in semiconductor lasers 2–16 , photovoltaics 17,18 , spintronics 19–21 , photodiodes 22–25 , and thermoelectrics 26 . Research on dilute bismide alloys has primarily focused to date on GaAs 1− x Bi x , where incorporation of Bi brings about a strong reduction of the direct Γ-point band gap ()–by up to 90 meV per % Bi at low Bi compositions x 27–31 –characterised by strong, composition-dependent bowing 29,32 .…”

Section: Introductionmentioning

confidence: 99%

Giant bowing of the band gap and spin-orbit splitting energy in GaP1−xBix dilute bismide alloys

Bushell

Broderick

Nattermann

et al. 2019

Sci Rep

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Using spectroscopic ellipsometry measurements on GaP 1− x Bi x /GaP epitaxial layers up to x = 3.7% we observe a giant bowing of the direct band gap ( ) and valence band spin-orbit splitting energy (Δ SO ). (Δ SO ) is measured to decrease (increase) by approximately 200 meV (240 meV) with the incorporation of 1% Bi, corresponding to a greater than fourfold increase in Δ SO in going from GaP to GaP 0.99 Bi 0.01 . The evolution of and Δ SO with x is characterised by strong, composition-dependent bowing. We demonstrate that a simple valence band-anticrossing model, parametrised directly from atomistic supercell calculations, quantitatively describes the measured evolution of and Δ SO with x . In contrast to the well-studied GaAs 1− x Bi x alloy , in GaP 1− x Bi x substitutional Bi creates localised impurity states lying energetically within the GaP host matrix band gap. This leads to the emergence of an optically active band of Bi-hybridised states, accounting for the overall large bowing of and Δ SO and in particular for the giant bowing observed for x ≲ 1%. Our analysis provides insight into the action of Bi as an isovalent impurity, and constitutes the first detailed experimental and theoretical analysis of the GaP 1− x Bi x alloy band structure.

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Enhancement of Rashba interaction in GaAs/AlGaAs quantum wells due to the incorporation of bismuth

Cited by 19 publications

References 27 publications

Reflectance anisotropy spectroscopy of strain-engineered GaAsBi alloys

Reflectance anisotropy spectroscopy of strain-engineered GaAsBi alloys

Bismuth content dependence of the electron spin relaxation time in GaAsBi epilayers and quantum well structures

Giant bowing of the band gap and spin-orbit splitting energy in GaP1−xBix dilute bismide alloys

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