Binding energy and stability of charged excitons in a semiconductor cylindrical quantum dot

Safwan, S.A.; Hekmat, Maryam; Asmaa, A.S.; El–Meshed, N.

doi:10.1016/j.physe.2008.06.016

Cited by 7 publications

(4 citation statements)

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“…There have been several reports on excitonic phenomena in 0D nanostructures where they are described as rectangular quantum boxes (QB) with a finite or infinite confinement barrier [1][2][3], spherical quantum dots with a rectangular potential barrier [4,5], parabolic [6][7][8] and gradual potential profile [9]. We found also a description of 0D nanostructures as cylindrical [10][11][12][13][14][15][16], conical [17], triangular [18], and lens-shaped quantum dots [19].…”

Section: Introductionmentioning

confidence: 59%

Exciton in Semiconductor Quantum Box: An Important Analytical Computational Step

Haddad¹

2023

Acta Phys. Pol. A

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A theoretical model to determine the properties of an exciton confined in a semiconductor quantum box with rectangular potential is presented. We have used the two-band model and the effective mass approximation. The theoretical approach includes a considerable analytic phase and makes it possible to reduce the numerical calculations. According to the new formulation, the limit cases for an exciton in a bulk semiconductor and an exciton confined in a two-dimensional structure are deduced, and a good agreement is shown in comparison with known results in the literature. We calculated the binding energy, spatial extension, and effective Bohr radius of the exciton. The variation law of the confined exciton energy, as a function of the dimension of the semiconductor quantum box, is established. The illustrations are given for a rectangular confining potential with finite and infinite barriers.

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Section: Introductionmentioning

confidence: 59%

Exciton in Semiconductor Quantum Box: An Important Analytical Computational Step

Haddad¹

2023

Acta Phys. Pol. A

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“…The eigenstates of the electron (hole) in the field of the exciton are described by the Schrödinger (7), which represents a motion of the projection of the electron (hole) on the plane of the excitonic QW. Using the polar coordinates r and φ and substituting Ψ e(h) (r, φ) = r −1/2 u e(h) (r, φ) into Eq.…”

Section: The Wave Function and Energy Of The Relative Motion Of The E...mentioning

confidence: 99%

“…The three-body problem for three electrons in a quantum dot in a magnetic field was solved in the framework of the hyperspherical functions method [17]. The variational method was applied to solve the eigenvalues and eigenfucntions problem for 3D X + and X − in cylindrical quantum dot [7]. A variational calculation of the ground-state energy of 2D neutral excitons, X + , and X − in a single QW was performed in Ref.…”

Section: Introductionmentioning

confidence: 99%

“…The experimental observation of trions in semiconductor quantum wells (QWs) was achieved in CdTe/CdZnTe [2] and in GaAs/AlGaAs [3][4][5].The many-body formalism including Feynman diagram technique was developed to study the collective properties of three-dimensional (3D) trions in the bulk semiconductors [6]. The 3D X + and X − confined in a semiconductor cylindrical quantum dot were investigated using a variational procedure within the effective mass approximation [7]. The 3D trions in bulk semiconductors [8] and two-dimensional trions [9] were studied theoretically.…”

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Trions in Coupled Quantum Wells and Wigner Crystallization

Berman

Kezerashvili

Tsiklauri

2014

Int. J. Mod. Phys. B

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We consider a restricted three body problem, where two interacted particles are located in two dimensional (2D) plane and interact with the third one located in the parallel spatially separated plane. The system of such type can be formed in the semiconductor coupled quantum wells, where the electrons (or holes) and direct excitons spatially separated in different parallel neighboring quantum wells that are sufficiently close to interact and form negative X − or positive X + indirect trions. It is shown that at large interwell separations, when the interwell separation much greater than the exciton Bohr radius, this problem can be solved analytically using the cluster approach. Analytical results for the energy spectrum and the wave functions of the spatially indirect trion are obtained, their dependence on the interwell separations is analyzed and a conditional probability distribution is calculated. The formation of 2D Wigner crystal of trions at the low densities is predicted. It is shown that the critical density of the formation of the trion Wigner crystal is sufficiently greater than the critical density of the electron Wigner crystal. PACS numbers: 71.35.Pq, 71.35.-y, 73.21.Fg I. INTRODUCTIONThe linear and nonlinear properties of semiconductor heterostructures are often governed by excitons that are defined as the bounded state of the electron-hole pair. This is especially important for semiconductors with widebandgap, where the excitonic binding energy is comparable to room temperature. Positively (X + ) and negatively (X − ) charged excitons, called trions in semiconductor structures, have been the subject of many experimental and theoretical studies in the last years. Positively charges excitons are formed by one electron and two holes, and negatively charged excitons are formed by two electrons and one hole. The theoretical proof of the stability of trions in bulk semiconductors was presented by Lampert [1]. The experimental observation of trions in semiconductor quantum wells (QWs) was achieved in CdTe/CdZnTe [2] and in GaAs/AlGaAs [3][4][5].The many-body formalism including Feynman diagram technique was developed to study the collective properties of three-dimensional (3D) trions in the bulk semiconductors [6]. The 3D X + and X − confined in a semiconductor cylindrical quantum dot were investigated using a variational procedure within the effective mass approximation [7]. The 3D trions in bulk semiconductors [8] and two-dimensional trions [9] were studied theoretically. According to these studies, the 2D trions have binding energies that are larger than the trions in the corresponding bulk materials. The 2D excitons and 2D X − in QWs in the presence of 2D electron gas were observed experimentally by optical measurements of an excitonic recombination line on the photoluminescence spectra from the QW [10]. The experiments devoted to the observation of 2D X − in QWs in magnetic field by studying the magneto-optical absorption spectra were performed in Ref. [2]. Besides, the 2D X − in QWs in magnetic fie...

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Z‐scheme CeO₂‐TiO₂@CNT Heterojunction for Efficient Photoredox Removal of Mix Pollutants (CPF, MB, MO, and RhB)

Kumar,

Sharma,

Mishra

et al. 2024

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Z‐scheme CeO2‐TiO2@CNT (CTC) heterojunction is fabricated using hydrothermal method and evaluated for removing mixed pollutants (MIX‐P) from ciprofloxacin (CPF) and textile contaminations. CTC demonstrated ≈99% removal efficiency against MIX‐P under solar irradiation of ≈105 lumens. High removal efficiency of CTC is attributed to reduced bandgap (Eg), 2.65 eV, and high specific surface area (68.193 m2 g−1). Lower Eg extends light absorption that generates more charge carriers and reactive species, RS (•O2−, h+, •OH), to facilitate the photocatalytic removal process. These RS are confirmed through trapping experiments using IPA, N2, and KI. Binding energies of 282.5, 283.7, and 285 eV, corresponding to Ti─C, Ti─O─C, and Ce─C bondings, indicated coupling of TiO2, CeO2, and CNT within the CTC structure. Ionic and pH tests confirmed lower photocatalytic efficiency of CTC in an alkaline environment. Photocurrent density and EIS measurements provide insights into the charge carrier dynamics, while HPLC‐MS analysis offered information on degradation pathway and identification of intermediates in the removal process. DFT studies confirmed the adjustments in electronic states, structural modifications, and band alignments in agreement with experimental results. This study highlights the potential of CTC as highly effective catalyst for sustainable removal of mixed pollutants from wastewater.

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Binding energy and stability of charged excitons in a semiconductor cylindrical quantum dot

Cited by 7 publications

References 29 publications

Exciton in Semiconductor Quantum Box: An Important Analytical Computational Step

Exciton in Semiconductor Quantum Box: An Important Analytical Computational Step

Trions in Coupled Quantum Wells and Wigner Crystallization

Z‐scheme CeO₂‐TiO₂@CNT Heterojunction for Efficient Photoredox Removal of Mix Pollutants (CPF, MB, MO, and RhB)

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Binding energy and stability of charged excitons in a semiconductor cylindrical quantum dot

Cited by 7 publications

References 29 publications

Exciton in Semiconductor Quantum Box: An Important Analytical Computational Step

Exciton in Semiconductor Quantum Box: An Important Analytical Computational Step

Trions in Coupled Quantum Wells and Wigner Crystallization

Z‐scheme CeO2‐TiO2@CNT Heterojunction for Efficient Photoredox Removal of Mix Pollutants (CPF, MB, MO, and RhB)

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Product

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Z‐scheme CeO₂‐TiO₂@CNT Heterojunction for Efficient Photoredox Removal of Mix Pollutants (CPF, MB, MO, and RhB)