Theoretical investigation of the effect of asymmetry on optical anisotropy and electronic structure of Stranski-Krastanov quantum dots

Kumar, Jitendra; Kapoor, Sahil; Gupta, Saral K.; Sen, Pranay K.

doi:10.1103/physrevb.74.115326

Cited by 41 publications

(28 citation statements)

References 49 publications

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“…In the present paper, we have also chosen a parabolic confinement potential. In order to make our theory self-contained, we have used the standard relevant equations [17,22]. The Hamiltonian used to obtain the energy eigenvalues comprises the Luttinger Hamiltonian H L and the confinement potential V x,y (x, y).…”

Section: Theoretical Formulationsmentioning

confidence: 99%

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Polarization rotation in asymmetric semiconductor quantum dots

Sen

Rana

Sen³

2010

Journal of Modern Optics

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Rotation of input polarization arising due to the recombination of electrons from the 1s-excitonic state to the hybrid valence band states have been theoretically examined in asymmetric semiconductor quantum dots. The Jones matrix calculations suggest that the polarization rotation directly depends on the asymmetry of the quantum dot and strength of hh-lh coupling. The results advocate the suitability of quantum dots as polarizing devices. IntroductionSemiconductor quantum dots (QDs) with sizes in the range of a few tens of nanometers have attracted much attention as possible candidate materials for quantum information processing [1,2]. The discrete and spin degenerate electronic energy levels of these QDs make them successful to manifest quantum coherence. Excitations corresponding to a specific spin state in a symmetric QD can be monitored by using suitable polarized light [3,4] and establish the QDs as useful hosts for the realization of quantum bits [5]. Symmetry plays an important role in determining the electronic spectra of QDs. According to the point symmetry C 2v in zinc blende based heterostructures, the interface induced hh-lh coupling is allowed and results in anisotropic exchange splitting of the excitonic levels. The in-plane symmetry is also lifted in a QD due to its shape and size anisotropy and adds to the exchange splitting [6][7][8]. The asymmetry in QDs is also responsible for (a) band mixing phenomenon [9,10], (b) spin splitting [4,11] and (c) modification in selection rules [12,13]. These phenomena are manifested in the experimental observations of the size and shape dependent polarization luminescence obtainable from the QDs. It is widely accepted that the electron-hole exchange interaction (EHEXI) causes coupling of jþ1i and jÀ1i optically active heavy hole exciton states and results in complex linear polarization of split fine structure components [14]. In zero magnetic field, the polarized luminescence appears as a result of optical spin orientation. The conservation of spin in photoabsorption allows spin orientation of excitons by polarized light beams and in effect exhibits

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Section: Theoretical Formulationsmentioning

confidence: 99%

“…As a consequence, the forbidden electronic transitions may become allowed [16]. Apart from this, the dimensions along the different coordinate axes are not the same in asymmetric QDs and lead to the anisotropy in the energy eigenvalues [17]. The in-plane anisotropy can also be explained on the single particle level.…”

Section: Introductionmentioning

confidence: 95%

Polarization rotation in asymmetric semiconductor quantum dots

Sen

Rana

Sen³

2010

Journal of Modern Optics

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“…The QDIP is studied with the k · p approach under the envelope function approximation [9]. The energy subbands and wavefunctions are obtained from the 4 × 4 Kohn-Luttinger Hamiltonian.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of II–VI Quantum Dot Infrared Photo-Detectors

Negi

Kumar

2015

Springer Proceedings in Physics

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We theoretically investigate the performance of a II-VI ZnCdSe/ZnSebased quantum dot infrared photodetector (QDIP) utilizing intersubband hole transitions in the valence band of the QDs to absorb infrared radiation. The analysis starts with the computation of band structure via multi-band effective mass model based on the Luttinger-Kohn Hamiltonian with the inclusion of strain effects. The theoretical formulation is further used to determine the spectral responsivity and dark current characteristics of the QDIP. IntroductionInfrared detectors are required in the various imaging applications, including medical diagnostics, astronomy, remote sensing, space-based surveillance, and thermal imaging [1]. Initially, infrared detectors were developed using narrow band gap semiconductors such as HgCdTe and InSb [2], which make use of interband transitions to detect the infrared radiation. Operating wavelength of these detectors can be modified by controlling the band gap of the semiconductor material via changing the alloys composition. However, the processing of narrow gap semiconductors creates problem in the epitaxial growth, non-uniformity, low yield and high cost [3]. Alternatively, intersubband transitions in the quantum hetero-structures have been utilized to detect the infrared radiation. The attractive feature of intersubband transition based detectors is that they do not require narrow band gap semiconductors. This provides flexibility to use any available wide band gap material to fabricate infrared detector. Moreover, quantum hetero-structure

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“…However, in the general case, the eigenfunctions have mixed heavy-hole/light-hole character. In case of sufficient valence-band mixing, the |⇓ heavy-hole state is a superposition involving some lighthole components which makes the previously forbidden transitions become optically weakly active 54,55 . The amount of mixing increases for decreasing splitting between the heavy-hole and light-hole bands, therefore the effective tensile strain we introduce could potentially increase the valence-band mixing.…”

Section: Beyond the Two-valence-bands Modelmentioning

confidence: 99%

Strain tuning of quantum dot optical transitions via laser-induced surface defects

et al. 2011

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We discuss the fine-tuning of the optical properties of self-assembled quantum dots by the strain perturbation introduced by laser-induced surface defects. We show experimentally that the quantum dot transition red-shifts, independently of the actual position of the defect, and that such frequency shift is about a factor five larger than the corresponding shift of a micropillar cavity mode resonance. We present a simple model that accounts for these experimental findings.

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Theoretical investigation of the effect of asymmetry on optical anisotropy and electronic structure of Stranski-Krastanov quantum dots

Cited by 41 publications

References 49 publications

Polarization rotation in asymmetric semiconductor quantum dots

Polarization rotation in asymmetric semiconductor quantum dots

Characteristics of II–VI Quantum Dot Infrared Photo-Detectors

Strain tuning of quantum dot optical transitions via laser-induced surface defects

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