Spin injection in lateral InAs quantum dot structures by optical orientation spectroscopy

Beyer, Jan; Buyanova, Irina; Suraprapapich, S.; Tu, C. W.; Chen, Weimin

doi:10.1088/0957-4484/20/37/375401

Cited by 12 publications

(9 citation statements)

References 31 publications

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“…2,3 However, there is still a need to take a closer look at the spin states during the injection of spin-polarized carriers or excitons, i.e., spin injection from a layered semiconductor barrier into a QD. [5][6][7][8][9][10] Such spin injection has the potential to provide the key to applying the spin states of QDs to spin-functional optical devices, as one would need to inject spin-polarized carriers from electrodes into QDs to achieve a practical device structure. Indeed, spin-polarized light emitting diodes and lasers based on QDs have been discussed; [11][12][13][14] however, spin injection is recognized as being much more difficult than spin-independent carrier injection due to the relative instability of the spin states in layered semiconductors, which allows them to easily relax during the injection process.…”

Section: Introductionmentioning

confidence: 99%

Growth-temperature dependence of optical spin-injection dynamics in self-assembled InGaAs quantum dots

Yamamura

Kiba

Yang

et al. 2014

Journal of Applied Physics

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Articles you may be interested inThe growth-temperature dependence of the optical spin-injection dynamics in self-assembled quantum dots (QDs) of In 0.5 Ga 0.5 As was studied by increasing the sheet density of the dots from 2 Â 10 10 to 7 Â 10 10 cm À2 and reducing their size through a decrease in growth temperature from 500 to 470 C. The circularly polarized transient photoluminescence (PL) of the resulting QD ensembles was analyzed after optical excitation of spin-polarized carriers in GaAs barriers by using rate equations that take into account spin-injection dynamics such as spin-injection time, spin relaxation during injection, spin-dependent state-filling, and subsequent spin relaxation. The excitation-power dependence of the transient circular polarization of PL in the QDs, which is sensitive to the state-filling effect, was also examined. It was found that a systematic increase occurs in the degree of circular polarization of PL with decreasing growth temperature, which reflects the transient polarization of exciton spin after spin injection. This is attributed to strong suppression of the filling effect for the majority-spin states as the dot-density of the QDs increases.

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Section: Introductionmentioning

confidence: 99%

Growth-temperature dependence of optical spin-injection dynamics in self-assembled InGaAs quantum dots

Yamamura

Kiba

Yang

et al. 2014

Journal of Applied Physics

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“…For excitation at energies higher than XL, e.g., when both hh and lh bands of the WL are involved, a lower spin polarization of photogenerated carriers is expected as both spin orientations are simultaneously created. 13 Indeed, the highest PL polarization degree was observed for excitation within the hh part of the WL alone. Under simultaneous excitation from both hh and lh bands in the WL, PL polarization is significantly reduced.…”

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confidence: 97%

Strong room-temperature optical and spin polarization in InAs/GaAs quantum dot structures

Beyer

Buyanova

Suraprapapich

et al. 2011

Applied Physics Letters

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Room-temperature optical and spin polarization up to 35% is reported in InAs/GaAs quantum dots in zero magnetic field under optical spin injection using continuous-wave optical orientation spectroscopy. The observed strong spin polarization is suggested to be facilitated by a shortened trion lifetime, which constrains electron spin relaxation. Our finding provides experimental demonstration of the highly anticipated capability of semiconductor quantum dots as highly polarized spin/light sources and efficient spin detectors, with efficiency greater than 35% in the studied quantum dots.Original Publication:Jan Beyer, Irina A Buyanova, S. Suraprapapich, C. W. Tu and Weimin Chen, Strong room-temperature optical and spin polarization in InAs/GaAs quantum dot structures, 2011, Applied Physics Letters, (98), 20, 203110.http://dx.doi.org/10.1063/1.3592572Copyright: American Institute of Physicshttp://www.aip.org

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“…With polarized nonresonant excitation, spin-polarized carriers are injected from the surrounding barrier into the QDs, and the initial spin coherence likely deteriorates during intra-relaxation through various elastic and inelastic scatterings with phonons. Because the exciton states are vulnerable to spin flip due to the electron-hole exchange interaction, it is known that the spins of uncorrelated separate electrons and holes are better conserved during spin injection than the spins of correlated electrons and holes in an exciton, and the same tendency was observed in different structures such as in QDs, laterally coupled QDs, and quantum rings 28 . Second, nonresonantly excited carriers are also known to affect the electric dipole of excitons via coherent many-body interactions in various quantum confinement structures [29][30][31] .…”

Section: Resultsmentioning

confidence: 99%

Optical shaping of the polarization anisotropy in a laterally coupled quantum dot dimer

et al. 2020

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We find that the emission from laterally coupled quantum dots is strongly polarized along the coupled direction [110], and its polarization anisotropy can be shaped by changing the orientation of the polarized excitation. When the nonresonant excitation is linearly polarized perpendicular to the coupled direction [110], excitons (X 1 and X 2) and local biexcitons (X 1 X 1 and X 2 X 2) from the two separate quantum dots (QD 1 and QD 2) show emission anisotropy with a small degree of polarization (10%). On the other hand, when the excitation polarization is parallel to the coupled direction [1 10], the polarization anisotropy of excitons, local biexcitons, and coupled biexcitons (X 1 X 2) is enhanced with a degree of polarization of 74%. We also observed a consistent anisotropy in the time-resolved photoluminescence. The decay rate of the polarized photoluminescence intensity along the coupled direction is relatively high, but the anisotropic decay rate can be modified by changing the orientation of the polarized excitation. An energy difference is also observed between the polarized emission spectra parallel and perpendicular to the coupled direction, and it increases by up to three times by changing the excitation polarization orientation from [110] to [110]. These results suggest that the dipole-dipole interaction across the two separate quantum dots is mediated and that the anisotropic wavefunctions of the excitons and biexcitons are shaped by the excitation polarization.

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Spin injection in lateral InAs quantum dot structures by optical orientation spectroscopy

Cited by 12 publications

References 31 publications

Growth-temperature dependence of optical spin-injection dynamics in self-assembled InGaAs quantum dots

Growth-temperature dependence of optical spin-injection dynamics in self-assembled InGaAs quantum dots

Strong room-temperature optical and spin polarization in InAs/GaAs quantum dot structures

Optical shaping of the polarization anisotropy in a laterally coupled quantum dot dimer

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