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de Simoni B, Rybak M, Antonatos N, Herman AP, Ciesiołkiewicz K, Tołłoczko AK, Peter M, Piejko A, Mosina K, Sofer Z, Kudrawiec R. Electronic Band Structure and Optical Properties of HgPS 3 Crystal and Layers. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2024; 128:9270-9280. [PMID: 38864003 PMCID: PMC11163980 DOI: 10.1021/acs.jpcc.4c00562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 04/19/2024] [Accepted: 05/15/2024] [Indexed: 06/13/2024]
Abstract
Transition metal thiophosphates (MPS3) are of great interest due to their layered structure and magnetic properties. Although HgPS3 may not exhibit magnetic properties, its uniqueness lies in its triclinic crystal structure and in the substantial mass of mercury, rendering it a compelling subject for exploration in terms of fundamental properties. In this work, we present comprehensive experimental and theoretical studies of the electronic band structure and optical properties for the HgPS3 crystal and mechanically exfoliated layers from a solid crystal. Based on absorption, reflectance and photoluminescence measurements supported by theoretical calculations, it is shown that the HgPS3 crystal has an indirect gap of 2.68 eV at room temperature. The direct gap is identified at the Γ point of the Brillouin zone (BZ) ≈ 50 meV above the indirect gap. The optical transition at the Γ point is forbidden due to selection rules, but the oscillator strength near the Γ point increases rapidly and therefore the direct optical transitions are visible in the reflectance spectra approximately at 60-120 meV above the absorption edge, across the temperature range of 40 to 300 K. The indirect nature of the bandgap and the selection rules for Γ point contribute to the absence of near-bandgap emission in HgPS3. Consequently, the photoluminescence spectrum is primarily governed by defect-related emission. The electronic band structure of HgPS3 undergoes significant changes when the crystal thickness is reduced to tri- and bilayers, resulting in a direct bandgap. Interestingly, in the monolayer regime, the fundamental transition is again indirect. The layered structure of the HgPS3 crystal was confirmed by scanning electron microscopy (SEM) and by mechanical exfoliation.
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Affiliation(s)
- Beatriz de Simoni
- Department
of Semiconductor Materials Engineering, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Miłosz Rybak
- Department
of Semiconductor Materials Engineering, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Nikolas Antonatos
- Department
of Semiconductor Materials Engineering, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
- Department
of Inorganic Chemistry, University of Chemistry
and Technology, 5 Technická, 166 28 Prague 6 - Dejvice, Czech Republic
| | - Artur P. Herman
- Department
of Semiconductor Materials Engineering, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Karolina Ciesiołkiewicz
- Department
of Semiconductor Materials Engineering, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Agata K. Tołłoczko
- Department
of Semiconductor Materials Engineering, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Maciej Peter
- Department
of Semiconductor Materials Engineering, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Adrianna Piejko
- Department
of Nanometrology, Wroclaw University of
Science and Technology, Janiszewskiego 11/17, 50-370 Wrocław, Poland
| | - Kseniia Mosina
- Department
of Inorganic Chemistry, University of Chemistry
and Technology, 5 Technická, 166 28 Prague 6 - Dejvice, Czech Republic
| | - Zdeněk Sofer
- Department
of Inorganic Chemistry, University of Chemistry
and Technology, 5 Technická, 166 28 Prague 6 - Dejvice, Czech Republic
| | - Robert Kudrawiec
- Department
of Semiconductor Materials Engineering, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
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Cordova DLM, Zhou Y, Milligan GM, Cheng L, Kerr T, Ziller J, Wu R, Arguilla MQ. Sensitive Thermochromic Behavior of InSeI, a Highly Anisotropic and Tubular 1D van der Waals Crystal. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2312597. [PMID: 38301612 DOI: 10.1002/adma.202312597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 01/08/2024] [Indexed: 02/03/2024]
Abstract
Thermochromism, the change in color of a material with temperature, is the fundamental basis of optical thermometry. A longstanding challenge in realizing sensitive optical thermometers for widespread use is identifying materials with pronounced thermometric optical performance in the visible range. Herein, it is demonstrated that single crystals of indium selenium iodide (InSeI), a 1D van der Waals (vdW) solid consisting of weakly bound helical chains, exhibit considerable visible range thermochromism. A strong temperature-dependent optical band edge absorption shift ranging from 450 to 530 nm (2.8 to 2.3 eV) over a 380 K temperature range with an experimental (dEg/dT)max value extracted to be 1.26 × 10-3 eV K-1 is shown. This value lies appreciably above most dense conventional semiconductors in the visible range and is comparable to soft lattice solids. The authors further seek to understand the origin of this unusually sensitive thermochromic behavior and find that it arises from strong electron-phonon interactions and anharmonic phonons that significantly broaden band edges and lower the Eg with increasing temperature. The identification of structural signatures resulting in sensitive thermochromism in 1D vdW crystals opens avenues in discovering low-dimensional solids with strong temperature-dependent optical responses across broad spectral windows, dimensionalities, and size regimes.
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Affiliation(s)
| | - Yinong Zhou
- Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA
| | - Griffin M Milligan
- Department of Chemistry, University of California, Irvine, CA, 92697, USA
| | - Leo Cheng
- Department of Chemistry, University of California, Irvine, CA, 92697, USA
| | - Tyler Kerr
- Department of Chemistry, University of California, Irvine, CA, 92697, USA
| | - Joseph Ziller
- Department of Chemistry, University of California, Irvine, CA, 92697, USA
| | - Ruqian Wu
- Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA
| | - Maxx Q Arguilla
- Department of Chemistry, University of California, Irvine, CA, 92697, USA
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Bayramov AH, Bagiyev EA, Alizade EH, Jalilli JN, Mamedov NT, Jahangirli ZA, Asadullayeva SG, Aliyeva YN, Cuscunà M, Lorenzo D, Esposito M, Balestra G, Simeone D, Tobaldi DM, Abou-Ras D, Schorr S. Two-Channel Indirect-Gap Photoluminescence and Competition between the Conduction Band Valleys in Few-Layer MoS 2. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 14:96. [PMID: 38202552 PMCID: PMC10780461 DOI: 10.3390/nano14010096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/20/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024]
Abstract
MoS2 is a two-dimensional layered transition metal dichalcogenide with unique electronic and optical properties. The fabrication of ultrathin MoS2 is vitally important, since interlayer interactions in its ultrathin varieties will become thickness-dependent, providing thickness-governed tunability and diverse applications of those properties. Unlike with a number of studies that have reported detailed information on direct bandgap emission from MoS2 monolayers, reliable experimental evidence for thickness-induced evolution or transformation of the indirect bandgap remains scarce. Here, the sulfurization of MoO3 thin films with nominal thicknesses of 30 nm, 5 nm and 3 nm was performed. All sulfurized samples were examined at room temperature with spectroscopic ellipsometry and photoluminescence spectroscopy to obtain information about their dielectric function and edge emission spectra. This investigation unveiled an indirect-to-indirect crossover between the transitions, associated with two different Λ and K valleys of the MoS2 conduction band, by thinning its thickness down to a few layers.
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Affiliation(s)
- Ayaz H. Bayramov
- Institute of Physics, Ministry of Science and Education, Baku Az1143, Azerbaijan; (A.H.B.); (E.H.A.); (S.G.A.)
| | - Elnur A. Bagiyev
- Institute of Physics, Ministry of Science and Education, Baku Az1143, Azerbaijan; (A.H.B.); (E.H.A.); (S.G.A.)
| | - Elvin H. Alizade
- Institute of Physics, Ministry of Science and Education, Baku Az1143, Azerbaijan; (A.H.B.); (E.H.A.); (S.G.A.)
| | - Javid N. Jalilli
- Institute of Physics, Ministry of Science and Education, Baku Az1143, Azerbaijan; (A.H.B.); (E.H.A.); (S.G.A.)
| | - Nazim T. Mamedov
- Institute of Physics, Ministry of Science and Education, Baku Az1143, Azerbaijan; (A.H.B.); (E.H.A.); (S.G.A.)
- Institute of Physical Problems, Baku State University, Ministry of Science and Education, Baku Az1148, Azerbaijan;
| | - Zakir A. Jahangirli
- Institute of Physics, Ministry of Science and Education, Baku Az1143, Azerbaijan; (A.H.B.); (E.H.A.); (S.G.A.)
- Institute of Physical Problems, Baku State University, Ministry of Science and Education, Baku Az1148, Azerbaijan;
| | - Saida G. Asadullayeva
- Institute of Physics, Ministry of Science and Education, Baku Az1143, Azerbaijan; (A.H.B.); (E.H.A.); (S.G.A.)
| | - Yegana N. Aliyeva
- Institute of Physical Problems, Baku State University, Ministry of Science and Education, Baku Az1148, Azerbaijan;
| | - Massimo Cuscunà
- National Research Council, Institute of Nanotechnology (NANOTEC), University c/o Campus Ecotekne, Via per Monteroni, 73100 Lecce, Italy; (D.L.); (M.E.); (G.B.); (D.S.); (D.M.T.)
| | - Daniela Lorenzo
- National Research Council, Institute of Nanotechnology (NANOTEC), University c/o Campus Ecotekne, Via per Monteroni, 73100 Lecce, Italy; (D.L.); (M.E.); (G.B.); (D.S.); (D.M.T.)
| | - Marco Esposito
- National Research Council, Institute of Nanotechnology (NANOTEC), University c/o Campus Ecotekne, Via per Monteroni, 73100 Lecce, Italy; (D.L.); (M.E.); (G.B.); (D.S.); (D.M.T.)
| | - Gianluca Balestra
- National Research Council, Institute of Nanotechnology (NANOTEC), University c/o Campus Ecotekne, Via per Monteroni, 73100 Lecce, Italy; (D.L.); (M.E.); (G.B.); (D.S.); (D.M.T.)
- Department of Mathematics and Physics ‘‘Ennio De Giorgi”, University of Salento, c/o Campus Ecotekne, Via per Monteroni, 73100 Lecce, Italy
| | - Daniela Simeone
- National Research Council, Institute of Nanotechnology (NANOTEC), University c/o Campus Ecotekne, Via per Monteroni, 73100 Lecce, Italy; (D.L.); (M.E.); (G.B.); (D.S.); (D.M.T.)
| | - David Maria Tobaldi
- National Research Council, Institute of Nanotechnology (NANOTEC), University c/o Campus Ecotekne, Via per Monteroni, 73100 Lecce, Italy; (D.L.); (M.E.); (G.B.); (D.S.); (D.M.T.)
| | - Daniel Abou-Ras
- Helmholtz-Zentrum Berlin for Materials and Energy (HZB), Department of Structure and Dynamics of Energy Materials, 14109 Berlin, Germany; (D.A.-R.); (S.S.)
| | - Susan Schorr
- Helmholtz-Zentrum Berlin for Materials and Energy (HZB), Department of Structure and Dynamics of Energy Materials, 14109 Berlin, Germany; (D.A.-R.); (S.S.)
- Institute of Geological Sciences, Free University of Berlin, 14195 Berlin, Germany
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Syperek M, Stühler R, Consiglio A, Holewa P, Wyborski P, Dusanowski Ł, Reis F, Höfling S, Thomale R, Hanke W, Claessen R, Di Sante D, Schneider C. Observation of room temperature excitons in an atomically thin topological insulator. Nat Commun 2022; 13:6313. [PMID: 36274087 PMCID: PMC9588767 DOI: 10.1038/s41467-022-33822-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Accepted: 10/04/2022] [Indexed: 11/23/2022] Open
Abstract
Optical spectroscopy of ultimately thin materials has significantly enhanced our understanding of collective excitations in low-dimensional semiconductors. This is particularly reflected by the rich physics of excitons in atomically thin crystals which uniquely arises from the interplay of strong Coulomb correlation, spin-orbit coupling (SOC), and lattice geometry. Here we extend the field by reporting the observation of room temperature excitons in a material of non-trivial global topology. We study the fundamental optical excitation spectrum of a single layer of bismuth atoms epitaxially grown on a SiC substrate (hereafter bismuthene or Bi/SiC) which has been established as a large-gap, two-dimensional (2D) quantum spin Hall (QSH) insulator. Strongly developed optical resonances are observed to emerge around the direct gap at the K and K’ points of the Brillouin zone, indicating the formation of bound excitons with considerable oscillator strength. These experimental findings are corroborated, concerning both the character of the excitonic resonances as well as their energy scale, by ab-initio GW and Bethe-Salpeter equation calculations, confirming strong Coulomb interaction effects in these optical excitations. Our observations provide evidence of excitons in a 2D QSH insulator at room temperature, with excitonic and topological physics deriving from the very same electronic structure. Here, the authors report the observation of room temperature excitons in a single layer of bismuth atoms epitaxially grown on a SiC substrate - a material of non-trivial global topology - with excitonic and topological physics deriving from the very same electronic structure.
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Lin DY, Hsu HP, Wang CW, Chen SW, Shih YT, Hwang SB, Sitarek P. Temperature-Dependent Absorption of Ternary HfS 2-xSe x 2D Layered Semiconductors. MATERIALS (BASEL, SWITZERLAND) 2022; 15:6304. [PMID: 36143616 PMCID: PMC9502516 DOI: 10.3390/ma15186304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 08/27/2022] [Accepted: 09/07/2022] [Indexed: 06/16/2023]
Abstract
In this study, we present the investigation of optical properties on a series of HfS2-xSex crystals with different Se compositions x changing from 0 to 2. We used the chemical-vapor transport method to grow these layered ternary compound semiconductors in bulk form. Their lattice constants and crystal properties were characterized by X-ray diffraction, high-resolution transmission electron microscopy, and Raman spectroscopy. We have performed absorption spectroscopies to determine their optical band-gap energies, which started from 2.012 eV with x = 0, and gradually shifts to 1.219 eV for x = 2. Furthermore, we measured the absorption spectroscopies at different temperatures in the range of 20-300 K to identify the temperature dependence of band-gap energies. The band-gap energies of HfS2-xSex were determined from the linear extrapolation method. We have noticed that the band-gap energy may be continuously tuned to the required energy by manipulating the ratio of S and Se. The parameters that describe the temperature influence on the band-gap energy are evaluated and discussed.
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Affiliation(s)
- Der-Yuh Lin
- Department of Electronic Engineering, National Changhua University of Education, Changhua City 50074, Taiwan
| | - Hung-Pin Hsu
- Department of Electronic Engineering, Ming Chi University of Technology, New Taipei City 243, Taiwan
| | - Cheng-Wen Wang
- Department of Electronic Engineering, National Changhua University of Education, Changhua City 50074, Taiwan
| | - Shang-Wei Chen
- Department of Electronic Engineering, National Changhua University of Education, Changhua City 50074, Taiwan
| | - Yu-Tai Shih
- Department of Physics, National Changhua University of Education, Changhua City 500207, Taiwan
| | - Sheng-Beng Hwang
- Department of Electronic Engineering, Chienkuo Technology University, Changhua City 500020, Taiwan
| | - Piotr Sitarek
- Department of Experimental Physics, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, 50370 Wrocław, Poland
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Kumar V, Mishra RK, Kumar P, Gwag JS. Electronic and optical properties of Nb/V-doped WS 2 monolayer: a first-principles study. LUMINESCENCE 2022. [PMID: 35856256 DOI: 10.1002/bio.4342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 07/08/2022] [Accepted: 07/17/2022] [Indexed: 11/12/2022]
Abstract
The electronic, dielectric, and optical properties of pure and Nb/V-doped WS2 monolayer are being investigated using the first-principles density functional theory (DFT). The electronic band structure calculations reveal that the pure and doped WS2 monolayer is a direct band gap semiconductor. It is seen that the doping not only slightly reduces the band gap but also changes the n-type character of pure WS2 monolayer to the p-type character. Hence, it may be useful for channel material in field effect transistors (FETs). Moreover, the optical studies reveal that the WS2 monolayer shows a significantly good optical response. However, a small ultraviolet shift is observed in the optical response of the doped case compared to the pristine WS2 monolayer. This study suggests that the WS2 monolayer can be a possible optical material for optoelectronic applications, and it can also be a replacement of MoS2 -based future electronics and optoelectronics.
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Affiliation(s)
- Vipin Kumar
- Department of Physics, Yeungnam University, Gyeongsan, Gyeongbuk, South Korea
| | | | - Pushpendra Kumar
- Department of Physics, Manipal University Jaipur, Jaipur, Rajasthan, India.,MSRC, Manipal University Jaipur, Jaipur, Rajasthan, India
| | - Jin Seog Gwag
- Department of Physics, Yeungnam University, Gyeongsan, Gyeongbuk, South Korea
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