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Steger M, Janke SM, Sercel PC, Larson BW, Lu H, Qin X, Yu VWZ, Blum V, Blackburn JL. On the optical anisotropy in 2D metal-halide perovskites. NANOSCALE 2022; 14:752-765. [PMID: 34940772 DOI: 10.1039/d1nr06899g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Two-dimensional metal-halide perovskites (MHPs) are versatile solution-processed organic/inorganic quantum wells where the structural anisotropy creates profound anisotropy in their electronic and excitonic properties and associated optical constants. We here employ a wholistic framework, based on semiempirical modeling (k·p/effective mass theory calculations) informed by hybrid density functional theory (DFT) and multimodal spectroscopic ellipsometry on (C6H5(CH2)2NH3)2PbI4 films and crystals, that allows us to link the observed optical properties and anisotropy precisely to the underlying physical parameters that shape the electronic structure of a layered MHP. We find substantial frequency-dependent anisotropy in the optical constants and close correspondence between experiment and theory, demonstrating a high degree of in-plane alignment of the two-dimensional planes in both spin-coated thin films and cleaved single crystals made in this study. Hybrid DFT results elucidate the degree to which organic and inorganic frontier orbitals contribute to optical transitions polarized along a particular axis. The combined experimental and theoretical approach enables us to estimate the fundamental electronic bandgap of 2.65-2.68 eV in this prototypical 2D perovskite and to determine the spin-orbit coupling (ΔSO = 1.20 eV) and effective crystal field (δ = -1.36 eV) which break the degeneracy of the frontier conduction band states and determine the exciton fine structure. The methods and results described here afford a better understanding of the connection between structure and induced optical anisotropy in quantum-confined MHPs, an important structure-property relationship for optoelectronic applications and devices.
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Affiliation(s)
- Mark Steger
- National Renewable Energy Laboratory, Golden, CO 80401, USA.
| | - Svenja M Janke
- Thomas Lord Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708, USA
- Institute of Advanced Study, University of Warwick, CV4 7AL Coventry, UK
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Peter C Sercel
- Center for Hybrid Organic Inorganic Semiconductors for Energy, Golden, CO, 80401, USA
| | - Bryon W Larson
- National Renewable Energy Laboratory, Golden, CO 80401, USA.
| | - Haipeng Lu
- National Renewable Energy Laboratory, Golden, CO 80401, USA.
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong
| | - Xixi Qin
- Thomas Lord Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708, USA
| | - Victor Wen-Zhe Yu
- Thomas Lord Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708, USA
| | - Volker Blum
- Thomas Lord Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708, USA
- Department of Chemistry, Duke University, Durham, NC 27708, USA
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Gasmi FZ, Chemam R, Graine R, Boubir B, Meradji H. Structural, electronic, and optical properties of the gallium nitride semiconductor by means of the FP-LAPW method. J Mol Model 2020; 26:356. [PMID: 33245412 DOI: 10.1007/s00894-020-04614-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 11/16/2020] [Indexed: 11/24/2022]
Abstract
In the present paper, the structural, electronic, and linear optical properties of different phases of the gallium nitride (GaN) have been investigated. The zinc blende and wurtzite phases of the GaN have been studied using the full-potential linearized augmented plane wave method (FP-LAPW). In our study, many approximations have been used, such as the local density approximation (LDA), the generalized gradient approximation (GGA), the Engel and Vosko generalized gradient approximation (EV-GGA), and the modified Becke-Johnson (mBJ) potential exchange. As a result, we found a very good agreement with literature experimental results for the energy band gap using the mBJ approximation with a scaling factor of 98% and 80% for the zinc blende and wurtzite phases, respectively.
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Affiliation(s)
- F Z Gasmi
- Radiation Physics Laboratory, Department of Physics, Faculty of Sciences, Badji Mokhtar University, Sidi Amar, Annaba, Algeria.,Research Center in Industrial Technologies, CRTI, Cheraga, P.O. Box 64, 16014, Algiers, Algeria
| | - R Chemam
- Radiation Physics Laboratory, Department of Physics, Faculty of Sciences, Badji Mokhtar University, Sidi Amar, Annaba, Algeria
| | - R Graine
- Radiation Physics Laboratory, Department of Physics, Faculty of Sciences, Badji Mokhtar University, Sidi Amar, Annaba, Algeria. .,Research Center in Industrial Technologies, CRTI, Cheraga, P.O. Box 64, 16014, Algiers, Algeria.
| | - B Boubir
- Research Center in Industrial Technologies, CRTI, Cheraga, P.O. Box 64, 16014, Algiers, Algeria
| | - H Meradji
- Radiation Physics Laboratory, Department of Physics, Faculty of Sciences, Badji Mokhtar University, Sidi Amar, Annaba, Algeria
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Gong SH, Ko SM, Jang MH, Cho YH. Giant Rabi Splitting of Whispering Gallery Polaritons in GaN/InGaN Core-Shell Wire. NANO LETTERS 2015; 15:4517-4524. [PMID: 26061117 DOI: 10.1021/acs.nanolett.5b01023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The hybrid nature of exciton polaritons opens up possibilities for developing a new concept nonlinear photonic device (e.g., polariton condensation, switching, and transistor) with great potential for controllability. Here, we proposed a novel type of polariton system resulting from strong coupling between a two-dimensional exciton and whispering gallery mode photon using a core-shell GaN/InGaN hexagonal wire. High quality, nonpolar InGaN multiple-quantum wells (MQWs) were conformally formed on a GaN core nanowire, which was spatially well matched with whispering gallery modes inside the wire. Both high longitudinal-transverse splitting of nonpolar MQWs and high spatial overlap with whispering gallery modes lead to unprecedented large Rabi splitting energy of ∼180 meV. This structure provides a robust polariton effect with a small footprint; thus, it could be utilized for a wide range of interesting applications.
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Affiliation(s)
- Su-Hyun Gong
- Department of Physics and KAIST Institute for the NanoCentury, KAIST, Daejeon 305-701, Republic of Korea
| | - Suk-Min Ko
- Department of Physics and KAIST Institute for the NanoCentury, KAIST, Daejeon 305-701, Republic of Korea
| | - Min-Ho Jang
- Department of Physics and KAIST Institute for the NanoCentury, KAIST, Daejeon 305-701, Republic of Korea
| | - Yong-Hoon Cho
- Department of Physics and KAIST Institute for the NanoCentury, KAIST, Daejeon 305-701, Republic of Korea
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Abstract
In this review paper we address one of the most rapidly developing new domains of semiconductor optics: light-matter coupling in semiconductor microcavities. Using the non-local dielectric response theory and transfer matrix technique, we show how two-dimensional confinement of a photonic mode coupled to an exciton resonance results in the appearance of two branches of exciton-polaritons, quasi-particles combining properties of photons and excitons. We obtain the dispersion relations of polaritons in microcavities and derive a condition for strong-weak coupling threshold. We show that being bosons, exciton-polaritons are subject to Bose-condensation which might result in emission of a coherent and monochromatic light in the strong coupling regime. A source of such coherent light is referred to as a polariton laser. We show that polariton lasers have theoretically no threshold and require essentially new basic physics as compared to conventional lasers described by Einstein theory. We give examples of model polariton laser structures expected to work at room temperature and overview the main difficulties on the way to producing these new opto-electronic devices.
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Savona V. Effect of interface disorder on quantum well excitons and microcavity polaritons. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2007; 19:295208. [PMID: 21483060 DOI: 10.1088/0953-8984/19/29/295208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The theory of the linear optical response of excitons in quantum wells and polaritons in planar semiconductor microcavities is reviewed, in the light of the existing experiments. For quantum well excitons, it is shown that disorder mainly affects the exciton centre-of-mass motion and is modelled by an effective Schrödinger equation in two dimensions. For polaritons, a unified model accounting for quantum well roughness and fluctuations of the microcavity thickness is developed. Numerical results confirm that polaritons are mostly affected by disorder acting on the photon component, thus confirming existing studies on the influence of exciton disorder. The polariton localization length is estimated to be in the few-micrometres range, depending on the amplitude of disorder, in agreement with recent experimental findings.
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Affiliation(s)
- Vincenzo Savona
- Institut de Théorie des Phénomènes Physiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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Gammon D, Snow ES, Shanabrook BV, Katzer DS, Park D. Homogeneous Linewidths in the Optical Spectrum of a Single Gallium Arsenide Quantum Dot. Science 1996; 273:87-90. [PMID: 8688056 DOI: 10.1126/science.273.5271.87] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The homogeneous linewidths in the photoluminescence excitation spectrum of a single, naturally formed gallium arsenide (GaAs) quantum dot have been measured with high spatial and spectral resolution. The energies and linewidths of the homogeneous spectrum provide a new perspective on the dephasing dynamics of the exciton in a quantum-confined, solid-state system. The origins of the linewidths are discussed in terms of the dynamics of the exciton in zero dimensions, in particular, in terms of lifetime broadening through the emission or absorption of phonons and photons.
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Affiliation(s)
- D Gammon
- Naval Research Laboratory, Washington, DC 20375, USA
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