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Mamindla R, Niranjan MK. Influence of temperature on bandgap shifts, optical properties and photovoltaic parameters of GaAs/AlAs and GaAs/AlSb p-nheterojunctions: insights from ab-initioDFT + NEGF studies. J Phys Condens Matter 2024; 36:205504. [PMID: 38330463 DOI: 10.1088/1361-648x/ad2793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Accepted: 02/08/2024] [Indexed: 02/10/2024]
Abstract
The III-V group semiconductors are highly promising absorbers for heterojunctions based solar cell devices due to their high conversion efficiency. In this work, we explore the solar cell properties and the role of electron-phonon coupling (EPC) on the solar cell parameters of GaAs/AlSb and GaAs/AlAsp-nheterojunctions using non-equilibrium Green function method (NEGF) in combination ofab-initiodensity functional theory (DFT). In addition, the band offsets at the heterointerfaces, optical absorption and bandgap shifts (BGSs) due to temperature are estimated using DFT + NEGF approach. The interface band gaps in heterostructures are found to be lower than bulk band gaps leading to a shift in optical absorption coefficient towards lower energy side that results in stronger photocurrent. The temperature dependent electronic BGS is significantly influenced by the phonon density and phonon energy via EPC. The phonon influenced BGS is found to change the optical absorption, photocurrent density and open-circuit voltage. In case of GaAs/AlSb junction, the interface phonons are found to have significantly higher energies as compared to the bulk phonons and thereby may have important implications for photovoltaic (PV) properties. Overall, the present study reveals the influence of EPC on the optical absorption and PV properties of GaAs/AlSb and GaAs/AlSbp-nheterojunctions. Furthermore, the study shows that the DFT + NEGF method can be successfully used to obtain the reasonable quantitative estimates of temperature dependent BGSs, optical absorption and PV properties ofp-nheterojunctions.
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Affiliation(s)
- Ramesh Mamindla
- Department of Physics, Indian Institute of Technology, Hyderabad, TS 502285, India
- Department of Humanities and Sciences, VNR Vignana Jyothi Institute of Engineering and Technology, Hyderabad, TS 500090, India
| | - Manish K Niranjan
- Department of Physics, Indian Institute of Technology, Hyderabad, TS 502285, India
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Rani D, Jana S, K Niranjan M, Samal P. First-principle investigation of structural, electronic, and phase stabilities in chalcopyrite semiconductors: insights from Meta-GGA functionals. J Phys Condens Matter 2024; 36:165502. [PMID: 38194716 DOI: 10.1088/1361-648x/ad1ca3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 01/09/2024] [Indexed: 01/11/2024]
Abstract
We undertake a comprehensive first-principles investigation into the factors influencing the optoelectronic efficiencies of PIQIIIR2VIchalcopyrite semiconductors. The structural attributes, electronic properties, and phase stabilities are explored using various meta-GGA exchange-correlation (XC) functionals within the density functional framework. In particular, we assess the relative performance of these XC functionals in obtaining estimates of various relevant parameters. The structural parameteruin chalcopyrite semiconductors is a noteworthy aspect, as it is intrinsically tied to the extent of orbital hybridization between distinct atoms and thereby strongly influences the electronic properties. In general, the application of widely used GGA-PBE XC functional to these chalcopyrites results in unreliable predictions of band gaps and 'u' parameter due to delocalization errors that in turn arise due to the inclusion ofdandfcore electrons. While hybrid functionals offer remarkable accuracy through state-of-the-art methods, their main drawback lies in their computational expense and resource demands. Our findings strongly suggest that in comparison to GGA-PBE, the meta-GGA XC functionals perform quite well and provide results that closely align with experimental values. In particular, ther2SCAN andrMGGAC XC functionals are preferable and superior for investigating chalcopyrites and other solid-state systems. This preference is rooted in their excellent performance and substantially reduced computational costs compared to hybrid functionals.
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Affiliation(s)
- Dimple Rani
- School of Physical Sciences, National Institute of Science Education and Research, An OCC of Homi Bhabha National Institute, Jatni 752050, India
| | - Subrata Jana
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Manish K Niranjan
- Department of Physics, Indian Institute of Technology, Hyderabad, India
| | - Prasanjit Samal
- School of Physical Sciences, National Institute of Science Education and Research, An OCC of Homi Bhabha National Institute, Jatni 752050, India
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Jana S, Yadav S, Swati, Niranjan MK, Prakash J. Ba 14Si 4Sb 8Te 32(Te 3): hypervalent Te in a new structure type with low thermal conductivity. Dalton Trans 2023; 52:15426-15439. [PMID: 37376920 DOI: 10.1039/d3dt01532g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2023]
Abstract
Heavier pnictogen (Sb, Bi) containing chalcogenides are well known for their complex structures and semiconducting properties for numerous applications, particularly thermoelectric materials. Here, we report the syntheses of single crystals and polycrystalline phases of a new complex quaternary polytelluride, Ba14Si4Sb8Te32(Te3), via a high-temperature reaction of elements. A single-crystal X-ray diffraction study showed that it crystallizes in an unprecedented structure type with monoclinic symmetry (space group: P21/c). The crystal structure of Ba14Si4Sb8Te32(Te3) consists of one-dimensional ∞1[Si4Sb8Te32(Te3)]28- stripes, which are separated by the Ba2+ cations. Its complex structure features linear polytelluride units of Te34- having intermediate Te⋯Te interactions. A polycrystalline Ba14Si4Sb8Te32(Te3) sample shows a direct narrow bandgap of 0.8(2) eV, which indicates its semiconducting nature. The electrical resistivity of a sintered pellet of the polycrystalline sample exponentially decreases from ∼39.3 Ωcm to ∼0.57 Ωcm on heating it from 323 K to 773 K, confirming the sample's semiconducting nature. The sign of Seebeck coefficient values is positive in the 323 K to 773 K range confirming the p-type nature of the sintered sample. Interestingly, the sample attains an extremely low thermal conductivity of ∼0.32 Wm-1K-1 at 773 K, which could be attributed to the lattice anharmonicity caused by the lone pair effect of Sb3+ species in its complex pseudo-one-dimensional crystal structure. The electronic band structure of the title phase and the strength of chemical bonding of pertinent atomic pairs have been evaluated theoretically using the DFT method.
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Affiliation(s)
- Subhendu Jana
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India.
| | - Sweta Yadav
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India.
| | - Swati
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India.
| | - Manish K Niranjan
- Department of Physics, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - Jai Prakash
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India.
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Panigrahi G, Yadav S, Jana S, Ramanujachary KV, Niranjan MK, Prakash J. Ba 4FeAgS 6: a new antiferromagnetic and semiconducting quaternary sulfide. Dalton Trans 2023; 52:621-634. [PMID: 36426633 DOI: 10.1039/d2dt03209k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The single crystals of a quaternary sulfide, Ba4FeAgS6, have been synthesized by reacting elements at 873 K inside a sealed fused silica tube. The title phase is the first ordered quaternary compound of the Ba-Ag-Fe-S system. The crystal structure of Ba4FeAgS6 is characterized by a single-crystal X-ray diffraction study at 298(2) K. It crystallizes in the space group C52h - P21/n of the monoclinic crystal system with unit cell dimensions of a = 8.6367(5) Å, b = 12.0291(7) Å, c = 13.2510(7) Å, and β = 109.015(2)°. This compound is stoichiometric, and its structure contains twelve unique crystallographic sites: four Ba, one Fe, one Ag, and six S sites. All atoms of the structure occupy the general positions. The Ba4FeAgS6 structure consists of one-dimensional chains of 1∞[FeAgS6]8- that are extended in the [100] direction. The negative charges on these chains are counterbalanced by the filling of Ba2+ cations in between the 1∞[FeAgS6]8- chains. The Fe atoms are bonded to four S atoms that form a distorted tetrahedral geometry around the central Fe atom. Each Ag atom in this structure is coordinated with four S atoms in a distorted tetrahedral fashion. These FeS4 and AgS4 motifs are the main building blocks of the Ba4FeAgS6 structure. The corner-sharing of FeS4 and AgS4 tetrahedra creates one-dimensional chains of 1∞[FeAgS6]8-. This structure does not contain any homoatomic or metallic bonds and can be charge-balanced as (Ba2+)4(Fe3+)1(Ag1+)1(S2-)6. The optical absorption study performed on a polycrystalline Ba4FeAgS6 sample reveals a direct bandgap of 1.2(1) eV. The magnetic studies reveal the antiferromagnetic behavior of Ba4FeAgS6 below 50 K. The thermal conductivity and theoretical electronic structure of Ba4FeAgS6 are also studied in detail.
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Affiliation(s)
- Gopabandhu Panigrahi
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India.
| | - Sweta Yadav
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India.
| | - Subhendu Jana
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India.
| | - K V Ramanujachary
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, New Jersey 08028, USA
| | - Manish K Niranjan
- Department of Physics, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - Jai Prakash
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India.
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Mamindla R, Ghosh A, Niranjan MK. Electron-phonon interaction effect on the photovoltaic parameters of indirect (direct) bandgap AlSb (GaSb) p-n junction solar cell devices: a density functional theoretical study. Phys Chem Chem Phys 2022; 24:24181-24191. [PMID: 36168865 DOI: 10.1039/d2cp03085c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Semiconductors AlSb and GaSb have emerged, in recent years, as important candidates for photovoltaic applications due to their strong absorption coefficients and other photovoltaic properties. In this study, AlSb (GaSb) p-n junction-based solar cell device parameters and properties are studied using the density functional theoretical framework and the non-equilibrium Green function approach. The effect of temperature on various solar cell parameters such as open-circuit voltage, power conversion efficiency, photocurrent density, short-circuit current, etc. is investigated using a special-thermal-displacement approach along with the GGA-1/2 exchange-correlation functional. As temperature increases, the phonons are found to significantly influence the charge carrier transport in the solar cells. The computed power conversion efficiencies for AlSb are estimated as 12.31% and 10.21% at 0 K and 400 K, respectively. The obtained results strongly indicate that the electron-phonon coupling and resulting phonon-assisted photon absorption are necessary for accurate description and prediction of solar cell properties. The estimates obtained in this study may serve as first-principles parameters with possible use in continuum model-based multiscale simulations of AlSb (GaSb) p-n homo-junction solar cells.
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Affiliation(s)
- Ramesh Mamindla
- Department of Physics, Indian Institute of Technology, Hyderabad, TS, 502285, India. .,Department of Physics, VNR Vignana Jyothi Institute of Engineering and Technology, Hyderabad 500090, TS, India.
| | - Arghya Ghosh
- Department of Physics, Indian Institute of Technology, Hyderabad, TS, 502285, India.
| | - Manish K Niranjan
- Department of Physics, Indian Institute of Technology, Hyderabad, TS, 502285, India.
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Ghosh A, Jana S, Rauch T, Tran F, Marques MAL, Botti S, Constantin L, Niranjan MK, Samal P. Efficient and improved prediction of the band offsets at semiconductorheterojunctions from meta-GGA density functionals: a benchmark study. J Chem Phys 2022; 157:124108. [DOI: 10.1063/5.0111693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Accurate theoretical prediction of the band offsets at interfaces of semiconductor heterostructures can of-ten be quite challenging. Although density functional theory has been reasonably successful to carry outsuch calculations and efficient and accurate semilocal functionals are desirable to reduce the computational cost. In general, the semilocal functionals based on the generalized gradient approximation (GGA) significantly underestimate the bulk band gaps. This, in turn, results in inaccurate estimates of the band offsets at the heterointerfaces. In this paper, we investigate the performance of several advanced meta-GGA functionals in the computational prediction of band offsets at semiconductor heterojunctions. In particular, we investigate the performance of r 2 SCAN (revised strongly-constrained and appropriately-normed functional), rMGGAC (revised semilocal functional based on cuspless hydrogen model and Pauli kinetic energy density functional), mTASK (modified Aschebrock and Kümmel meta-GGA functional), and LMBJ (local modified Becke-Johnson) exchange-correlation functionals. Our results strongly suggest that these meta-GGA functionals for supercell calculations perform quite well, especially, when compared to computationally more demanding GW calculations. We also present band offsets calculated using ionization potentials and electron affinities, as well as band alignment via the branch point energies. Overall, our study shows that the aforementioned meta-GGA functionals can be used within the DFT framework to estimate the band offsets in semiconductor heterostructures with predictive accuracy.
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Affiliation(s)
| | - Subrata Jana
- Department of Chemistry and Biochemistry, The Ohio State University, United States of America
| | - Tomas Rauch
- Friedrich Schiller Universität Jena Institut für Festkörpertheorie und -optik, Germany
| | - Fabien Tran
- Institute of Materials Chemistry, Vienna University of Technology, Austria
| | | | - Silvana Botti
- Institut für Festkörpertheorie und -optik, Friedrich Schiller Universität Jena Institut für Festkörpertheorie und -optik, Germany
| | - Lucian Constantin
- Department of Physics, Istituto di Nanoscienze, Consiglio Nazionale delle Ricerche CNR-NANO, 41125 Modena, Italy, Italy
| | | | - Prasanjit Samal
- School of Physical Sciences, National Institute of Science Education and Research, India
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Jana S, Panigrahi G, Tripathy B, Malladi SK, Sundaramoorthy M, Arumugam S, Niranjan MK, Prakash J. Synthesis, characterization, and electronic structure of SrBi2S4. J SOLID STATE CHEM 2022. [DOI: 10.1016/j.jssc.2022.123250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Jana S, Panigrahi G, Tripathy B, Malladi SK, Niranjan MK, Prakash J. A new non-stoichiometric quaternary sulfide Ba3.14(4)Sn0.61(1)Bi2.39(1)S8: Synthesis, crystal structure, physical properties, and electronic structure. J SOLID STATE CHEM 2022. [DOI: 10.1016/j.jssc.2022.122914] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Panigrahi G, Yadav S, Jana S, Ghosh A, Niranjan MK, Prakash J. Syntheses and characterization of two new layered ternary chalcogenides NaScQ 2 (Q = Se and Te). NEW J CHEM 2022. [DOI: 10.1039/d2nj04783g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Two new metal ternary chalcogenides, NaScSe2 and NaScTe2, have been synthesized via high-temperature reaction.
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Affiliation(s)
- Gopabandhu Panigrahi
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana, 502284, India
| | - Sweta Yadav
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana, 502284, India
| | - Subhendu Jana
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana, 502284, India
| | - Arghya Ghosh
- Department of Physics, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana, 502284, India
| | - Manish K. Niranjan
- Department of Physics, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana, 502284, India
| | - Jai Prakash
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana, 502284, India
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Yadav S, Jana S, Panigrahi G, Malladi SK, Niranjan MK, Prakash J. Five coordinated Mn in Ba 4Mn 2Si 2Te 9: synthesis, crystal structure, physical properties, and electronic structure. Dalton Trans 2022; 51:9265-9277. [DOI: 10.1039/d2dt01167k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new structure type Ba4Mn2Si2Te9 containing unique MnTe5 units is synthesized. The structure comprises two independent Mn atoms, each with 50% occupancy. It is a narrow bandgap semiconductor (Eg = 0.6(1) eV) consistent with the DFT studies.
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Affiliation(s)
- Sweta Yadav
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - Subhendu Jana
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - Gopabandhu Panigrahi
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - Sairam K. Malladi
- Department of Materials Science & Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - Manish K. Niranjan
- Department of Physics, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - Jai Prakash
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
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Jana S, Panigrahi G, Ishtiyak M, Narayanswamy S, Bhattacharjee PP, Niranjan MK, Prakash J. Germanium Antimony Bonding in Ba 4Ge 2Sb 2Te 10 with Low Thermal Conductivity. Inorg Chem 2021; 61:968-981. [PMID: 34961320 DOI: 10.1021/acs.inorgchem.1c02990] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new quaternary telluride, Ba4Ge2Sb2Te10, was synthesized at high temperature via the reaction of elements. A single-crystal X-ray diffraction study shows that the title compound crystallizes in its own structure type in the monoclinic P21/c space group having cell dimensions of a = 13.984(3) Å, b = 13.472(3) Å, c = 13.569(3) Å, and β = 90.16(3)° with four formula units per unit cell (Z = 4). The pseudo-one-dimensional crystal structure of Ba4Ge2Sb2Te10 consists of infinite 1∞[Ge2Sb2Te10]8- stripes, which are separated by Ba2+ cations. Each of the Ge(1) atoms is covalently bonded to four Te atoms, whereas the Ge(2) atom is covalently bonded with one Sb(2) and three Te atoms in a distorted tetrahedral geometry. The title compound is the first example of a chalcogenide that shows Ge-Sb bonding. The Sb(1) atom is present at the center of the seesaw geometry of four Te atoms. In contrast, the Sb(2) atom forms a seesaw geometry by coordinating with one Ge(2) and three Te atoms. Condensation of these Ge and Sb centered polyhedral units lead to the formation of 1∞[Ge2Sb2Te10]8- stripes. The temperature-dependent resistivity study suggests the semimetallic/degenerate semiconducting nature of polycrystalline Ba4Ge2Sb2Te10. The positive sign of Seebeck coefficient values indicates that the predominant charge carriers are holes in Ba4Ge2Sb2Te10. An extremely low lattice thermal conductivity of ∼0.34 W/mK at 773 K was observed for polycrystalline Ba4Ge2Sb2Te10, which is presumably due to the lattice anharmonicity induced by the stereochemically active 5s2 lone pair of Sb. The electronic structure of Ba4Ge2Sb2Te10 and the bonding of atom pairs in the structure have been analyzed by means of ELF analysis and crystal orbital Hamilton population (COHP) analysis.
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Affiliation(s)
- Subhendu Jana
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - Gopabandhu Panigrahi
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - Mohd Ishtiyak
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - Sake Narayanswamy
- Department of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - Pinaki P Bhattacharjee
- Department of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - Manish K Niranjan
- Department of Physics, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - Jai Prakash
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
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Ghosh A, Jana S, Niranjan MK, Behera SK, Constantin LA, Samal P. Improved electronic structure prediction of chalcopyrite semiconductors from a semilocal density functional based on Pauli kinetic energy enhancement factor. J Phys Condens Matter 2021; 34:075501. [PMID: 34768248 DOI: 10.1088/1361-648x/ac394d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 11/12/2021] [Indexed: 06/13/2023]
Abstract
The correct treatment ofdelectrons is of prime importance in order to predict the electronic properties of the prototype chalcopyrite semiconductors. The effect ofdstates is linked with the anion displacement parameteru, which in turn influences the bandgap of these systems. Semilocal exchange-correlation functionals which yield good structural properties of semiconductors and insulators often fail to predict reasonableubecause of the underestimation of the bandgaps arising from the strong interplay betweendelectrons. In the present study, we show that the meta-generalized gradient approximation (meta-GGA) obtained from the cuspless hydrogen density (MGGAC) (2019Phys. Rev.B 100 155140) performs in an improved manner in apprehending the key features of the electronic properties of chalcopyrites, and its bandgaps are comparative to that obtained using state-of-art hybrid methods. Moreover, the present assessment also shows the importance of the Pauli kinetic energy enhancement factor,α= (τ-τW)/τunifin describing thedelectrons in chalcopyrites. The present study strongly suggests that the MGGAC functional within semilocal approximations can be a better and preferred choice to study the chalcopyrites and other solid-state systems due to its superior performance and significantly low computational cost.
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Affiliation(s)
- Arghya Ghosh
- Department of Physics, Indian Institute of Technology, Hyderabad, India
| | - Subrata Jana
- School of Physical Sciences, National Institute of Science Education and Research, HBNI, Bhubaneswar 752050, India
- Department of Chemistry & Biochemistry, The Ohio State University, Columbus, OH 43210, United States of America
| | - Manish K Niranjan
- Department of Physics, Indian Institute of Technology, Hyderabad, India
| | - Sushant Kumar Behera
- School of Physical Sciences, National Institute of Science Education and Research, HBNI, Bhubaneswar 752050, India
| | - Lucian A Constantin
- Istituto di Nanoscienze, Consiglio Nazionale delle Ricerche CNR-NANO, 41125 Modena, Italy
| | - Prasanjit Samal
- School of Physical Sciences, National Institute of Science Education and Research, HBNI, Bhubaneswar 752050, India
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Niranjan MK, Ghosh A. Theoretical investigation of lattice dynamics, infrared reflectivity, polarized Raman spectra and nature of interlayer coupling in two-dimensional layered gallium sulfide. J Phys Condens Matter 2021; 33:405001. [PMID: 34256354 DOI: 10.1088/1361-648x/ac13fa] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 07/13/2021] [Indexed: 06/13/2023]
Abstract
Gallium sulfide (GaS) is a highly promising two-dimensional layered semiconductor owing to its remarkable thickness dependent electronic and physical properties. In this article, we perform a comprehensiveab initiostudy of lattice dynamics, mode symmetry assignments, polarized Raman and infrared (IR) reflectivity spectra of GaS system. Polarized Raman spectra are obtained for different light polarization set-ups of incoming and scattered light. The frequencies of all allowed vibrational modes at the zone-centre are calculated and symmetry labels are assigned. Furthermore, the variation of frequencies & intensities of Raman/IR active modes of ultrathin GaS films (few layers) as function of film thickness is studied. In addition, we also explore the nature of weak interlayer coupling in GaS. The weak forces between the GaS layers are usually assumed to be due to interlayer van der Waals (vdW) interaction. However, this assumption has not been reasonably explained in reported experimental studies. Our study strongly suggests that weak interlayer interactions in GaS may be primarily electrostatic (Coulomb) in nature and therefore the contribution of vdW interactions to layer-layer coupling and lattice dynamics may be significantly lower than that of electrostatic interaction. The suggested nature of interlayer coupling in GaS and related III-VI semiconductors may have important implications in determination of their various physical properties.
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Affiliation(s)
- Manish K Niranjan
- Department of Physics, Indian Institute of Technology, Hyderabad, India
| | - Arghya Ghosh
- Department of Physics, Indian Institute of Technology, Hyderabad, India
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Panigrahi G, Jana S, Ishtiyak M, Narayanswamy S, Bhattacharjee PP, Ramanujachary KV, Niranjan MK, Prakash J. Ba 2Ln 1-xMn 2Te 5 (Ln = Pr, Gd, and Yb; x = Ln vacancy): syntheses, crystal structures, optical, resistivity, and electronic structure. Dalton Trans 2021; 50:6688-6701. [PMID: 33908515 DOI: 10.1039/d1dt00057h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Three new isostructural quaternary tellurides, Ba2Ln1-xMn2Te5 (Ln = Pr, Gd, and Yb), have been synthesized by the molten-flux method at 1273 K. The single-crystal X-ray diffraction studies at 298(2) K showed that Ba2Ln1-xMn2Te5 crystallize in the space group -C2/m of the monoclinic crystal system. There are six unique crystallographic sites in this structure's asymmetric unit: one Ba site, one Ln site, one Mn site, and three Te sites. The Ln site in the Ba2Ln1-xMn2Te5 structure is partially filled, which leaves about one-third of the Ln sites vacant (□) for Pr and Gd compounds. These structures do not contain any homoatomic or metallic bonding and can be charge-balanced as (Ba2+)2(Gd/Pr3+)2/3(Mn2+)2(Te2-)5. The refined composition for the Yb compound is Ba2Yb0.74(1)Mn2Te5 and can be charge-balanced with a mixed valence state of Yb2+/Yb3+. The crystal structures of Ba2Ln1-xMn2Te5 consist of complex layers of [Ln1-xMn2Te5]4- stacked along the [100] direction, with Ba2+ cations separating these layers. The Ln atoms are bound to six Te atoms that form a distorted octahedral geometry around the central Ln atom. Each Mn atom in this structure is coordinated to four Te atoms in a distorted tetrahedral fashion. These LnTe6 and MnTe4 units are the main building blocks of the Ba2Ln1-xMn2Te5 structure. The optical absorption study performed on a polycrystalline Ba2Gd2/3Mn2Te5 sample reveals a direct bandgap of 1.06(2) eV consistent with the DFT study. A semiconducting behavior was also observed for polycrystalline Ba2Gd2/3Mn2Te5 from the resistivity study. The temperature-dependent magnetic studies on a polycrystalline sample of Ba2Gd2/3Mn2Te5 did not reveal any long-range magnetic order down to 5 K. The effective magnetic moment (μeff) of 10.37μB calculated using the Curie-Weiss law is in good agreement with the theoretical value (μcal) of 10.58μB.
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Affiliation(s)
- Gopabandhu Panigrahi
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502285, India.
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Ishtiyak M, Jana S, Karthikeyan R, Ramesh M, Tripathy B, Malladi SK, Niranjan MK, Prakash J. Syntheses of five new layered quaternary chalcogenides SrScCuSe3, SrScCuTe3, BaScCuSe3, BaScCuTe3, and BaScAgTe3: crystal structures, thermoelectric properties, and electronic structures. Inorg Chem Front 2021. [DOI: 10.1039/d1qi00717c] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Five new layered transition metal-based chalcogenides (SrScCuSe3, SrScCuTe3, BaScCuSe3, BaScCuTe3, and BaScAgTe3) were discovered by the exploratory solid-state method.
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Affiliation(s)
- Mohd Ishtiyak
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502285, India
| | - Subhendu Jana
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502285, India
| | - R. Karthikeyan
- Department of Physics, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502285, India
| | - M. Ramesh
- Department of Physics, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502285, India
| | - Bikash Tripathy
- Department of Materials Science & Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502285, India
| | - Sairam K. Malladi
- Department of Materials Science & Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502285, India
| | - Manish K. Niranjan
- Department of Physics, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502285, India
| | - Jai Prakash
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502285, India
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Panigrahi G, Jana S, Narayanswamy S, Bhattacharjee PP, Niranjan MK, Prakash J. Reactive molten-flux assisted syntheses of single crystals of Cs 19Ln 19Mn 10Te 48 (Ln = Pr and Gd) crystallizing in a new structure type. CrystEngComm 2021. [DOI: 10.1039/d1ce00950h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two new complex layered quaternary tellurides, Cs19Ln19Mn10Te48 (Ln = Pr and Gd), were synthesized by the reactive molten flux method. The title compounds represent an unprecedented structure type.
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Affiliation(s)
- Gopabandhu Panigrahi
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - Subhendu Jana
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - S. Narayanswamy
- Department of Materials Science & Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - Pinaki P. Bhattacharjee
- Department of Materials Science & Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - Manish K. Niranjan
- Department of Physics, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
| | - Jai Prakash
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502284, India
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Borisevich AY, Chang HJ, Huijben M, Oxley MP, Okamoto S, Niranjan MK, Burton JD, Tsymbal EY, Chu YH, Yu P, Ramesh R, Kalinin SV, Pennycook SJ. Suppression of octahedral tilts and associated changes in electronic properties at epitaxial oxide heterostructure interfaces. Phys Rev Lett 2010; 105:087204. [PMID: 20868130 DOI: 10.1103/physrevlett.105.087204] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Indexed: 05/29/2023]
Abstract
Epitaxial oxide interfaces with broken translational symmetry have emerged as a central paradigm behind the novel behaviors of oxide superlattices. Here, we use scanning transmission electron microscopy to demonstrate a direct, quantitative unit-cell-by-unit-cell mapping of lattice parameters and oxygen octahedral rotations across the BiFeO3-La0.7 Sr0.3 MnO3 interface to elucidate how the change of crystal symmetry is accommodated. Combined with low-loss electron energy loss spectroscopy imaging, we demonstrate a mesoscopic antiferrodistortive phase transition near the interface in BiFeO3 and elucidate associated changes in electronic properties in a thin layer directly adjacent to the interface.
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Affiliation(s)
- A Y Borisevich
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
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Niranjan MK, Wang Y, Jaswal SS, Tsymbal EY. Prediction of a switchable two-dimensional electron gas at ferroelectric oxide interfaces. Phys Rev Lett 2009; 103:016804. [PMID: 19659167 DOI: 10.1103/physrevlett.103.016804] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Indexed: 05/28/2023]
Abstract
The demonstration of a quasi-two-dimensional electron gas (2DEG) in LaAlO3/SrTiO3 heterostructures has stimulated intense research activity in recent years. The 2DEG has unique properties that are promising for applications in all-oxide electronic devices. For such applications it is desirable to have the ability to control 2DEG properties by external stimulus. Here, based on first-principles calculations we predict that all-oxide heterostructures incorporating ferroelectric constituents, such as KNbO3/ATiO3 (A=Sr, Ba, Pb), allow creating a 2DEG switchable between two conduction states by ferroelectric polarization reversal. The effect occurs due to the screening charge at the interface that counteracts the depolarizing electric field and depends on polarization orientation. The proposed concept of ferroelectrically controlled interface conductivity offers the possibility to design novel electronic devices.
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Affiliation(s)
- Manish K Niranjan
- Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, USA
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Velev JP, Duan CG, Burton JD, Smogunov A, Niranjan MK, Tosatti E, Jaswal SS, Tsymbal EY. Magnetic tunnel junctions with ferroelectric barriers: prediction of four resistance States from first principles. Nano Lett 2009; 9:427-432. [PMID: 19113889 DOI: 10.1021/nl803318d] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Magnetic tunnel junctions (MTJs), composed of two ferromagnetic electrodes separated by a thin insulating barrier layer, are currently used in spintronic devices, such as magnetic sensors and magnetic random access memories. Recently, driven by demonstrations of ferroelectricity at the nanoscale, thin-film ferroelectric barriers were proposed to extend the functionality of MTJs. Due to the sensitivity of conductance to the magnetization alignment of the electrodes (tunneling magnetoresistance) and the polarization orientation in the ferroelectric barrier (tunneling electroresistance), these multiferroic tunnel junctions (MFTJs) may serve as four-state resistance devices. On the basis of first-principles calculations, we demonstrate four resistance states in SrRuO(3)/BaTiO(3)/SrRuO(3) MFTJs with asymmetric interfaces. We find that the resistance of such a MFTJ is significantly changed when the electric polarization of the barrier is reversed and/or when the magnetizations of the electrodes are switched from parallel to antiparallel. These results reveal the exciting prospects of MFTJs for application as multifunctional spintronic devices.
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Affiliation(s)
- Julian P Velev
- Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588-0111, USA.
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