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Phong TC, Phuc HV, Phuong LTT. Electron-phonon coupling effect on the optical absorption of gated β 12-borophene. Phys Chem Chem Phys 2024; 26:18983-18988. [PMID: 38953345 DOI: 10.1039/d4cp02153c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
This study addresses the effect of electron-phonon coupling (EPC) on the electro-optical properties of gated β12-borophene. The focus is on how EPC influences the orbital hybridization of boron atoms, particularly within the Bariśic-Labbe-Friedel-Su-Schrieffer-Heeger framework, and considers the role of gate electrodes in this process. The results reveal a redshift in the optical spectrum only when there is positive feedback from one electrode on EPC. In other configurations, except for the y-direction, a blueshift spectrum is observed. The study emphasizes the importance of tuning these spectral shifts for maximizing the performance of solar cells in converting sunlight into usable energy.
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Affiliation(s)
- Tran Cong Phong
- Atomic Molecular and Optical Physics Research Group, Institute for Advanced Study in Technology, Ton Duc Thang University, Ho Chi Minh City, Vietnam.
- Faculty of Electrical and Electronics Engineering, Ton Duc Thang University, Ho Chi Minh City, Vietnam
| | - Huynh V Phuc
- Division of Theoretical Physics, Dong Thap University, Cao Lanh 870000, Vietnam
| | - Le T T Phuong
- Faculty of of Physics, University of Education, Hue University, Hue, 530000, Vietnam.
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Hieu NN, Phuc HV, Hoi BD. Electronic phase transition in bilayer P6 mmm borophene. Phys Chem Chem Phys 2024; 26:18892-18897. [PMID: 38949400 DOI: 10.1039/d4cp01484g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
In this study, using the tight-binding model and Green's function technique, we investigate potential electronic phase transitions in bilayer P6mmm borophene under the influence of external stimuli, including a perpendicular electric field, electron-hole coupling between sublayers (excitonic effects), and dopants. Our focus is on key electronic properties such as the band structure and density of states. Our findings reveal that the pristine lattice is metal with Dirac cones around the Fermi level, where their intersection forms a nodal line. The system undergoes transitions to a semiconducting state - elimination of nodal line - with a perpendicular electric field and a semimetallic state - transition from two Dirac cones to a single Dirac cone - with combined electric field and excitonic effects. Notably, with these, the system retains its massless Dirac-like bands characteristic at finite energy. However, introducing a dopant still leads to a metallic phase, but the Dirac-like bands become massive. Considering all these effects, the system ultimately reaches a semiconducting phase with massive Dirac-like bands. These results hold significance for optoelectronic applications.
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Affiliation(s)
- Nguyen N Hieu
- Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam
- Faculty of Natural Sciences, Duy Tan University, Da Nang 550000, Vietnam
| | - Huynh V Phuc
- Division of Physics, School of Education, Dong Thap University, Cao Lanh 870000, Vietnam
| | - Bui D Hoi
- Faculty of of Physics, University of Education, Hue University, Hue 530000, Vietnam.
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Hap DC, Hung LPQ, Tung LT, Phuong LTT, Phong TC. Adjustment of optical absorption in phosphorene through electron-phonon coupling and an electric field. Phys Chem Chem Phys 2024; 26:11825-11832. [PMID: 38566602 DOI: 10.1039/d4cp00167b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
This study investigates the optical absorption of monolayer phosphorene, focusing on its response to the electron-phonon coupling (EPC) and an electric field. Using a tight-binding Hamiltonian model based on the Barišic-Labbe-Friedel-Su-Schrieffer-Heeger model and the Kubo formula, we calculate the electronic band structure and optical absorption characteristics. The anisotropic dispersion of carriers along armchair and zigzag directions leads to distinct optical responses. Positive and negative EPC effects increase and decrease hopping parameters, respectively, enlarging and reducing/closing the band gap. Moreover, both EPCs cause an admixture of blue and red shift spectrum along the armchair direction, while a red (blue) shift spectrum is observed for positive (negative) EPC along the zigzag direction. Incorporating electric field effects in the EPC increases band gaps for both positive and negative EPC activities, resulting in shifted optical peaks along both directions.
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Affiliation(s)
- Do C Hap
- Faculty of Physics, University of Education, Hue University, Hue, 530000, Vietnam
| | - Le P Q Hung
- Faculty of Physics, University of Education, Hue University, Hue, 530000, Vietnam
| | - Luong T Tung
- Faculty of Physics, University of Education, Hue University, Hue, 530000, Vietnam
| | - Le T T Phuong
- Faculty of Physics, University of Education, Hue University, Hue, 530000, Vietnam
| | - Tran Cong Phong
- Atomic Molecular and Optical Physics Research Group, Institute for Advanced Study in Technology, Ton Duc Thang University, Ho Chi Minh City, Vietnam.
- Faculty of Electrical and Electronics Engineering, Ton Duc Thang University, Ho Chi Minh City, Vietnam
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Hoi BD, Phuong LTT, Dung PV, Phong TC. Substrate-induced strain and exchange field effects on the electronic and thermal properties of monolayer β 12-borophene. Phys Chem Chem Phys 2024; 26:7611-7617. [PMID: 38363118 DOI: 10.1039/d3cp06225b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
The recently uncovered two-dimensional materials serve as versatile building blocks for electronic devices. In this study, we methodically investigate the impact of substrate-induced strain and exchange field effects on the electronic density of states (EDOS) and electronic heat capacity (EHC) of single-layer β12-borophene. Utilizing the Green's function approach, we compute these functions. The van Hove singularities in EDOS are observed to shift with strain, and depending on the direction and strength of the exchange field, the number of singularities increases. All these responses can be attributed to the renormalization of the velocity of electronic bands. Additionally, the inherent Schottky anomaly (an unusual peak at low temperatures) in the EHC undergoes a notable shift to higher and lower temperatures and variations in the intensity of the EHC due to substrate effects.
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Affiliation(s)
- Bui Dinh Hoi
- Faculty of Physics, University of Education, Hue University, Hue, 530000, Vietnam
| | - Le Thi Thu Phuong
- Faculty of Physics, University of Education, Hue University, Hue, 530000, Vietnam
| | | | - Tran Cong Phong
- Atomic Molecular and Optical Physics Research Group, Institute for Advanced Study in Technology, Ton Duc Thang University, Ho Chi Minh City, Vietnam.
- Faculty of Electrical and Electronics Engineering, Ton Duc Thang University, Ho Chi Minh City, Vietnam
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Chen C, Yang Z, Liu R, Xue L, Xu LC. Insights into electron dynamics in two-dimensional bismuth oxyselenide: a monolayer-bilayer perspective. Phys Chem Chem Phys 2024; 26:5438-5446. [PMID: 38275150 DOI: 10.1039/d3cp05357a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2024]
Abstract
Bismuth oxyselenide (Bi2O2Se), an emerging 2D semiconductor material, has garnered substantial attention owing to its remarkable properties, including air stability, elevated carrier mobility, and ultrafast optical response. In this study, we conduct a comparative analysis of electron excitation and relaxation processes in monolayer and bilayer Bi2O2Se. Our findings reveal that monolayer Bi2O2Se exhibits parity-forbidden transitions between the band edges at the Γ point, whereas bilayer Bi2O2Se demonstrates parity activity, providing the bilayer with an advantage in light absorption. Employing nonadiabatic molecular dynamics simulations, we uncover a two-stage hot-electron relaxation process-initially fast followed by slow-in both monolayer and bilayer Bi2O2Se within the conduction band. Despite the presence of weak nonadiabatic coupling between the CBM + 1 and CBM, limiting hot electron relaxation, the monolayer displays a shorter relaxation time due to its higher phonon-coupled frequency and smaller energy difference. Our investigation sheds light on the layer-specific excitation properties of 2D Bi2O2Se layered materials, providing crucial insights for the strategic design of photonic devices utilizing 2D materials.
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Affiliation(s)
- Cuifan Chen
- College of Physics, Taiyuan University of Technology, Jinzhong 030600, China.
| | - Zhi Yang
- College of Physics, Taiyuan University of Technology, Jinzhong 030600, China.
| | - Ruiping Liu
- College of Physics, Taiyuan University of Technology, Jinzhong 030600, China.
| | - Lin Xue
- College of Physics, Taiyuan University of Technology, Jinzhong 030600, China.
| | - Li-Chun Xu
- College of Physics, Taiyuan University of Technology, Jinzhong 030600, China.
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Thakur T, Szafran B. Nagaoka ferromagnetism in an array of phosphorene quantum dots. Sci Rep 2023; 13:18796. [PMID: 37914768 PMCID: PMC10620429 DOI: 10.1038/s41598-023-45860-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 10/25/2023] [Indexed: 11/03/2023] Open
Abstract
We consider an array of four quantum dots defined in phosphorene containing three excess electrons, i.e., in the conditions of near half filling when itinerant Nagaoka ferromagnetism is expected to appear in a square array with isotropic interdot hopping. The interdot hopping in the array arranged in a square inherits the anisotropy from the form of the phosphorene conduction band. We apply the configuration interaction method for discussion of the appearance and stability of the spin-polarized ground state and discuss the compensation of the effective mass anisotropy by the geometry of the quantum dot array. Our study shows strong stability of Nagaoka ferromagnetism for optimized geometry of the array, with the Nagaoka gap as large as ∼ 230 µeV. A phase diagram for the ground-state spin ordering versus the geometric parameters of the array is presented. We study the suppression of the ferromagnetism in a transition of the [Formula: see text] array to a quasi-1D chain and indicate that the shift of one of the quantum dots away from the array center is enough to transform the system to a quantum dot chain. A shift in the zigzag crystal direction induces the low-spin ground state more effectively than a shift along the armchair direction. We also discuss the robustness of the spin ordering against detuning one of the dots. The ferromagnetic ground-state survives as long as the detuning is not large enough to trap one of the electrons within a single quantum dot (for positive detuning) or remove one of the quantum dots of the accessible energy range (for negative detuning).
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Affiliation(s)
- Tanmay Thakur
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, al. Mickiewicza 30, 30-059, Kraków, Poland
| | - Bartłomiej Szafran
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, al. Mickiewicza 30, 30-059, Kraków, Poland.
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Phong TC, Lam VT, Hoi BD. Tuning electronic phase in noncentrosymmetric quantum spin Hall insulators through physical stimuli. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:325502. [PMID: 34044386 DOI: 10.1088/1361-648x/ac05e4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 05/27/2021] [Indexed: 06/12/2023]
Abstract
In this work, the perturbation-induced phase transitions in noncentrosymmetric quantum spin Hall insulators (QSHIs) are analytically addressed. In particular, the dilute charged impurity, the electric field, and the Zeeman splitting field are considered within the tight-binding Hamiltonian model, Green's function approach, and the Born approximation. Following theC3vsymmetry breaking in the PbBiI compound as a representative QSHI, the band gap becomes larger via the electric field, while the system transits to the semimetallic phase via the dilute charged impurities and Zeeman field, modifying the degenerate states in the electronic density of states. While the coexistence of electric field and impurities demonstrate that the system backs to its initial semiconducting phase, the combined Zeeman field and impurities do not alter the robust semimetallic phase.
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Affiliation(s)
- Tran C Phong
- Center for Theoretical and Computational Physics, University of Education, Hue University, Hue 530000, Viet Nam
| | - Vo T Lam
- Faculty of Natural Sciences Pedagogy, Sai Gon University, 273 An Duong Vuong Str., District 5, Ho Chi Minh City, Vietnam
| | - Bui D Hoi
- Center for Theoretical and Computational Physics, University of Education, Hue University, Hue 530000, Viet Nam
- Department of Physics, University of Education, Hue University, Hue 530000, Vietnam
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