Insights from Experiment and Theory on Peculiarities of the Electronic Structure and Optical Properties of the Tl2HgGeSe4 Crystal

Tuan V Vu; Oleg Khyzhun; Galyna L Myronchuk; Mariana Denysyuk; Lyudmyla Piskach; Andrij O Selezen; Ilona Radkowska; Anatolii O Fedorchuk; Svitlana S Petrovska; Vira A Tkach; Michał Piasecki

doi:10.1021/acs.inorgchem.3c01756

Insights from Experiment and Theory on Peculiarities of the Electronic Structure and Optical Properties of the Tl₂HgGeSe₄ Crystal

Inorg Chem. 2023 Oct 16;62(41):16691-16709. doi: 10.1021/acs.inorgchem.3c01756. Epub 2023 Oct 4.

Authors

Tuan V Vu^{1

2}, Oleg Khyzhun^{3

4}, Galyna L Myronchuk⁴, Mariana Denysyuk⁴, Lyudmyla Piskach⁵, Andrij O Selezen⁵, Ilona Radkowska⁶, Anatolii O Fedorchuk⁷, Svitlana S Petrovska³, Vira A Tkach³, Michał Piasecki^{6

8}

Affiliations

¹ Laboratory for Computational Physics, Institute for Computational Science and Artificial Intelligence, Van Lang University, 70000 Ho Chi Minh City, Vietnam.
² Faculty of Mechanical─Electrical and Computer Engineering, School of Technology, Van Lang University, 70000 Ho Chi Minh City, Vietnam.
³ Frantsevych Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3 Krzhyzhanovsky Street, 03142 Kyiv, Ukraine.
⁴ Department of Experimental Physics and Information-Measuring Technology, Lesya Ukrainka Volyn National University, 13 Voli Avenue, 43025 Lutsk, Ukraine.
⁵ Department of Chemistry and Technology, Lesya Ukrainka Volyn National University, 13 Voli Avenue, 43025 Lutsk, Ukraine.
⁶ Jan Dlugosz University in Częstochowa, Armii Krajowej 13/15, PL-42-217 Częstochowa, Poland.
⁷ Department of Inorganic and Organic Chemistry, Lviv National University of Veterinary Medicine and Biotechnologies, 50 Pekarska Street, 79010 Lviv, Ukraine.
⁸ Inorganic Chemistry Department, Uzhhorod National University, 46 Pidhirna, UA-88000 Uzhhorod, Ukraine.

Abstract

Tl₂HgGeSe₄ crystal was successfully, for the first time, synthesized by the Bridgman-Stockbarger technology, and its electronic structure and peculiarities of optical constants were investigated using both experimental and theoretical techniques. The present X-ray photoelectron spectroscopy measurements show that the Tl₂HgGeSe₄ crystal reveals small moisture sensitivity at ambient conditions and that the essential covalent constituent of the chemical bonding characterizes it. The latter suggestion was supported theoretically by ab initio calculations. The present experiments feature that the Tl₂HgGeSe₄ crystal is a high-resistance semiconductor with a specific electrical conductivity of σ ∼ 10^-8 Ω^-1 cm^-1 (at 300 K). The crystal is characterized by p-type electroconductivity with an indirect energy band gap of 1.28 eV at room temperature. It was established that a good agreement with the experiments could be obtained when performing first-principles calculations using the modified Becke-Johnson functional as refined by Tran-Blaha with additional involvement in the calculating procedure of the Hubbard amendment parameter U and the impact of spin-orbit coupling (TB-mBJ + U + SO model). Under such a theoretical model, we have determined that the energy band gap of the Tl₂HgGeSe₄ crystal is equal to 1.114 eV, and this band gap is indirect in nature. The optical constants of Tl₂HgGeSe₄ are calculated based on the TB-mBJ + U + SO model.