Manifestation of Point Defects in the Electronic Structure of Hg3Te2Cl2 Crystals

  • O. V. Bokotey Faculty of Physics, Uzhhorod National University
  • V. V. Vakulchak Faculty of Physics, Uzhhorod National University
  • A. A. Bokotey Faculty of Physics, Uzhhorod National University
  • I. I. Nebola Faculty of Physics, Uzhhorod National University
Keywords: band structure, point defects, gap, absorption edge, optical transitions

Abstract

Within the score of the density functional theory, we investigate the impact of point defects on the electronic structure of Hg3Te2Cl2 crystals, by using the supercell model [2×2×1]. The ab initio calculations for defect-free and defective Hg3Te2Cl2 crystals in the LDA approximation are performed for the first time, by using the quantum-chemical software package SIESTA. The studied crystal possesses an indirect band gap. According to the analysis of the obtained data, the indirect gap is equal to 2.628 eV, while the direct gap is 2.714 eV. The influence of vacancy defects on the conductive and optical properties of Hg3Te2Cl2 crystals is discussed in detail. The tellurium and chlorine vacancy defect states indicate the presence of additional energy levels below the bottom of the conduction band edge. We have shown that only tellurium vacancies produce the additional energy levels in a vicinity of the valence band maximum. It is found that the presence of point defects in Hg3Te2Cl2 changes the direction of optical transitions. Therefore, the defective crystal is a direct gap semiconductor. The satisfactory agreement with the experimental data is obtained.

References

O.V. Bokotey, Investigation of gyrotropic properties for Hg3Te2Cl2 (X = Se, Te) crystals, J. Alloys Compd. 678, 444 (2016) [DOI: 10.1016/j.jallcom.2016.04.018].

O.V. Bokotey, Theoretical calculations of refractive properties for Hg3Te2Cl2 crystals, Nanoscale Res. Lett. 11, 251 (2016) [DOI: 10.1186/s11671-016-1476-8].

O.V. Bokotey, K.E. Glukhov, I.I. Nebola, and A.A. Bokotey, First-principles calculations of phonons and Raman spectra in the Hg3Te2Cl2 crystals, J. Alloys Compd. 669, 161 (2016) [DOI: 10.1016/ j.jallcom. 2016.02.005].

O.V. Bokotey, I.P. Studenyak, I.I. Nebola, and Yu.V. Minets, Theoretical study of structural features and optical properties of the Hg3Te2Cl2 polymorphs, J. Alloys Compd. 660, 193 (2016) [DOI: 10.1016/ j.jallcom. 2015.11.086].

R. Nitsche, Crystal growth and optical properties of mercury-telluro-chloride, Hg3Te2Cl2, Mater. Res. Bull. 7, 679 (1972) [DOI: http: 10.1016/0025-5408(72) 90056-6].

Yu.V. Voroshilov, Z.P. Hadmashi, and V.O. Hudolii, Production and natural optical activity of mercury chalcogenhalogenides, Neorg. Mater. 17, 2022 (1981).

O.V. Bokotey, Refractive index behavior of mercury chalcogenhalogenides Hg3Te2Cl2, in Proceedings of Ukrainian-German Symposium on Physics and Chemistry of Nanostructures and on Nanobiotechnology, Kyiv, Ukraine, September 21–25, 2015, p. 140.

P. Hohenberg and W. Kohn, Inhomogeneous electron gas, Phys. Rev. B 136, 864 (1964) [DOI: 10.1103/PhysRev.136.B864].

W. Kohn and L.J. Sham, Self-consistent equations including exchange and correlation effects, Phys. Rev. 140, A1133 (1965) [DOI: 10.1103/PhysRev.140.A1133].

D.M. Ceperley and B.J. Alder, Ground state of the electron gas by a stochastic method, Phys. Rev. Lett. 45, 566 (1980) [DOI: 10.1103/PhysRevLett.45.566].

J.P. Perdew and A. Zunger, Self-interaction correction to density-functional approximations for many-electron systems, Phys. Rev. B. 23, 5048 (1981) [DOI: 10.1103/PhysRevB.23.5048].

J.M. Soler, E. Artacho, J.D. Gale, A. Garc´ıa, J. Junquera, P. Ordej´on, and D. S´anchez-Portal, The SIESTA method for ab initio order-N materials simulation, J. Phys.: Condens. Matter. 14, 11, 2745 (2002), arXiv: condmat/0111138v1[cond-mat.mtrl-sci].

G.B. Bachelet, D.R. Hamann, and M. Schl¨uter, Pseudopotentials that work: From H to Pu, Phys. Rev. B 26, 8, 4199 (1982).

C. Hartwigsen, S. Goedecker, and J. Hutter, Relativistic separable dual-space Gaussian pseudopotentials from H to Rn, Phys. Rev. B 58, 7, 3641 (1998) [DOI: 10.1103/PhysRevB.58.3641].

Z.P. Hadmashi and L.M. Suslikov, Absorption edge of Hg3Te2Cl2 crystals, Fiz. Tverd. Tela 26, 2, 592 (1984).

O.V. Bokotey, V.V. Vakulchak, and I.I. Nebola, Electronic structure of mercury chalcogenhalogenides Hg3Te2Cl2, in Proceedings of Ukrainian-German Symposium on Physics and Chemistry of Nanostructures and on Nanobiotechnology, Kyiv, Ukraine, September 21–25, 2015, p. 139.

O.V. Bokotey, V.V. Vakulchak, and I.I. Nebola, Influence of defects on the band structure of Hg3X2Y2 (X = S, Se, Te; Y = F, Cl, Br, I) crystals, in Proceedings of the XXth International Seminar on Physics and Chemistry of Solids, Lviv, Ukraine, September 12–15, 2015, p. 69.

O.V. Bokotey, V.V. Vakulchak, I.I. Nebola, and A.A. Bokotey, Band structure and optical transitions in the Hg3Te2Cl2 crystals, J. Phys. Chem. Sol. 99, 153 (2016) [DOI: 10.1016/j.jpcs.2016.08.016].

Published
2019-01-04
How to Cite
Bokotey, O., Vakulchak, V., Bokotey, A., & Nebola, I. (2019). Manifestation of Point Defects in the Electronic Structure of Hg3Te2Cl2 Crystals. Ukrainian Journal of Physics, 61(10), 901. https://doi.org/10.15407/ujpe61.10.0901
Section
Solid matter