Manifestation of Point Defects in the Electronic Structure of Hg3Te2Cl2 Crystals

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.

Origin of electronic properties of α-Hg3S2Cl2 polymorph

“…7,8 In general, the whole region of valence states has a complex hybrid character caused by the interaction of all atoms species inherent to the crystals of the Hg3X2Y2 type. The analysis of rotation dispersion 16 of α-Hg3S2Cl2 and our DFT calculations indicates that the rotation of polarization plane in this crystal is connected with direct optical transitions.…”

“…The corderoite family compounds are characterized by such optical properties as high refractive index and photoconductivity [1][2][3] and are materials showing presence of optical activity and electro-optic effect. [4][5][6][7][8][9][10] The main structural feature of mentioned crystals is the tendency to formation of various polymorphic modifications. At the same time due to the wide transparency in the visible and IR-range (from 0.3 to 40 m) their optoelectronic features are very useful for possible applications.…”