ELECTRONIC STRUCTURE AND OPTICAL SPECTRA OF AG3SBS3 CRYSTAL IN THE MONOCLINIC PHASE
Keywords:
semiconductor, pyrargyrite, density functional theory, band structure, dielectric functionAbstract
The work is devoted to the theoretical study of the features of the structure, electronic states, and optical properties of the ternary chalcogenide semiconductor Ag3SbS3, which has a crystal structure with a space group of symmetry P21/с. The study was conducted using the methodology from first principles. Calculations were carried out within the framework of the density functional theory (DFT) and the Kohn-Sham formalism using the local density approximation and the generalized gradient approximation to describe the exchange-correlation interaction between electrons. In order to find the equilibrium parameters of the lattice and the atomic coordinates, before calculating the properties of the crystal, a geometric optimization of the crystal structure was carried out using the Broyden-Fletcher-Goldfarb-Schenno algorithm. The theoretically obtained structural parameters of the crystal are in good agreement with the experimental data. For the first time, the band-energy structure of the Ag3SbS3 crystal in the monoclinic phase was studied. It was found that the E(k) band structure is characterized by a relatively weak dispersion of the conduction band and valence band levels. The top of the valence band is formed by a wide band from 0 to –5 eV. The band gap is of an indirect type. The calculated values of the band gap Eg are 1.1 eV for LDA and 1.4 eV for GGA functionals. The structure of the electronic levels of the investigated compound was analyzed from the calculations of the full and partial density of states of the crystal. It was found that the top of the valence band is formed by p-states of sulfur and antimony atoms. The bottom of the conduction band is formed by equal s-states of silver and p-states of Sb. A significant similarity between the electronic structure of the crystal in the monoclinic phase and the tetragonal phase is shown. Milliken charges and bond occupancy were calculated, which confirmed their ionic-covalent nature. The optical spectra of the Ag3SbS3 crystal in the monoclinic phase were calculated and analyzed.
References
Schönau K. A., Redfern S. A. T. High-temperature phase transitions, dielectric relaxation, and ionic mobility of proustite, Ag3AsS3, and pyrargyrite, Ag3SbS3, Journal of Applied Physics. 2002. 92 P. 7415–7424.
Gandrud W. B., Boyd G. D., McFee J. H., Wehmeier F. H. Nonlinear optical properties of Ag3SbS3, Appl. Phys. Lett. 1970. 16. P. 59–61.
Petrov V., Noack F., Tunchev I., Schunemann P., Zawilski K. The nonlinear coefficient d36 of CdSiP2, in: Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications VIII, SPIE, 2009. P. 157–164.
Dmitriev V. G., Gurzadyan G. G., Nikogosyan D. N., Handbook of Nonlinear Optical Crystals, Springer, Berlin, Heidelberg, 1999. P. 1–2.
Rudysh M. Ya., Myronchuk G. L., Fedorchuk A. O., Marchuk O. V., Kordan V. M., Kohan O. P., Myronchuk D. B., Smitiukh O. V. Electronic structure and optical properties of the Ag3SbS3 crystal: experimental and DFT studies, Phys. Chem. Chem. Phys. 2023. 25. P. 22900–22912.
Kutoglu A. Die Struktur des Pyrostilpnits (Feuerblende) Ag3SbS3., Phase Transition. 1992. 38. P. 127–120.
Segall M. D., Lindan P. J. D., Probert M. J., Pickard C. J., Hasnip P. J., Clark S. J., Payne M. C. First-principles simulation: ideas, illustrations and the CASTEP code, J. Phys.: Condens. Matter. 2002. 14. P. 2717–2744.
Lee J. G. Computational Materials Science: An Introduction, accessed October 1, 2020).
Ceperley D. M., Alder B. J. Ground State of the Electron Gas by a Stochastic Method, Phys. Rev. Lett. 1980. 45. P. 566–569.
Perdew J. P., Zunger A. Self-interaction correction to density-functional approximations for many-electron systems, Phys. Rev. B. 1981. 23. P. 5048–5079.
Perdew J. P., Burke K., Ernzerhof M. Generalized Gradient Approximation Made Simple, Phys. Rev. Lett. 1996. 77. P. 3865–3868.
Perdew J. P., Ruzsinszky A., Csonka G. I., Vydrov O. A., Scuseria G. E., Constantin L. A., Zhou X., Burke K. Restoring the Density-Gradient Expansion for Exchange in Solids and Surfaces, Phys. Rev. Lett. 2008. 100. P. 136406.
Vanderbilt D. Soft self-consistent pseudopotentials in a generalized eigenvalue formalism, Phys. Rev. B. 1990. 41. P. 7892–7895.
Pfrommer B. G., Côté M., Louie S. G., Cohen M. L. Relaxation of Crystals with the Quasi-Newton Method, Journal of Computational Physics. 1997. 131. P. 233–240.
Rudysh M. Ya., Shchepanskyi P. A., Fedorchuk A. O., Brik M. G., Stadnyk V. Yo., Myronchuk G. L., Kotomin E. A., Piasecki M. Impact of anionic system modification on the desired properties for CuGa(S1−xSex)2 solid solutions, Computational Materials Science. 2021. 196. P. 110553.
Kashuba A. I., Piasecki M., Bovgyra O. V., Stadnyk V. Yo., Demchenko P., Fedorchuk A., Franiv A. V., Andriyevsky B. Specific Features of Content Dependences for Energy Gap in InxTl1-x I Solid State Crystalline Alloys, Acta Phys. Pol. A. 2018. 133. P. 68–75.
Ilchuk H., Andriyevsky B., Kushnir O., Kashuba A., Semkiv I., Petrus R., Electronic band structure of cubic solidstate CdTe1-xSex solutions, Ukr. J. Phys. Opt. 2021. 22. P. 101–109.
Kohn W., Sham L. J. Self-Consistent Equations Including Exchange and Correlation Effects, Phys. Rev. 1965. 140. P. A1133–A1138.
Chrunik M., Majchrowski A., Ozga K., Rudysh M. Ya., Kityk I. V., Fedorchuk A. O., Stadnyk V. Yo., Piasecki M. Significant photoinduced increment of reflectivity coefficient in LiNa5Mo9O30, Current Applied Physics. 2017. 17. P. 1100–1107.
Fox M. Optical Properties of Solids, Second Edition, Oxford University Press, Oxford, New York, 2010.
