X-ray Photoelectron Spectrum and Electronic Properties of a Noncentrosymmetric Chalcopyrite Compound HgGa₂S₄: LDA, GGA, and EV-GGA

Abstract

An all electron full potential linearized augmented plane wave method has been applied for a theoretical study of the band structure, density of states, and electron charge density of a noncentrosymmetric chalcopyrite compound HgGa(2)S(4) using three different approximations for the exchange correlation potential. Our calculations show that the valence band maximum (VBM) and conduction band minimum (CBM) are located at Gamma resulting in a direct energy gap of about 2.0, 2.2, and 2.8 eV for local density approximation (LDA), generalized gradient approximation (GGA), and Engel-Vosko (EVGGA) compared to the experimental value of 2.84 eV. We notice that EVGGA shows excellent agreement with the experimental data. This agreement is attributed to the fact that the Engel-Vosko GGA formalism optimizes the corresponding potential for band structure calculations. We make a detailed comparison of the density of states deduced from the X-ray photoelectron spectra with our calculations. We find that there is a strong covalent bond between the Hg and S atoms and Ga and S atoms. The Hg-Hg, Ga-Ga, and S-S bonds are found to be weaker than the Hg-S and Ga-S bonds showing that a covalent bond exists between Hg and S atoms and Ga and S atoms.

Effect of increasing tellurium content on the electronic and optical properties of cadmium selenide telluride alloys CdSe1−xTex: An ab initio study

“…2 shows the band structure of the alloys for various Te content. For the cubic structure with the increasing Te content the band gap is decreased in agreement with the previous calculations using the same approach [7] Previous studies [27,28] have shown that the use of the LDA and GGA usually leads to underestimate the energy band gaps in semiconductors. Moreover, both of LDA and GGA functional are based on simple model assumptions which are not sufficiently flexible for accurate reproduction of the exchange correlation energy and its charge space derivative.…”

Evidence of “new hot spots” from determining the nonlinear optical behavior of materials: mechanistic studies of the vanadium borate crystal, Na3VO2B6O11

“…Borate materials, which are crystallographic noncentrosymmetric (NCS), have attracted considerable interest for their potential characteristics, especially in the second-order nonlinear optical (NLO) activity. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Introducing NCS building units has become an extremely important way of obtaining NCS structures, 18,[19][20][21][22][23][24] such as acentrically distorted units with octahedral coordinated d 0 transition metals (Nb 5+ , V 5+ , etc.) or lone-pair active cations (Pb 2+ , Bi 3+ ) due to the second-order Jahn-Teller (SOJT) effect.…”

Theoretical study on pressure‐induced phase transition and thermal properties of HgAl2Se4

“…At a pressure of about 13 GPa the BCT phase has also been reported to undergo a rocksalt‐type phase transition 4. Recently, a growing interest has been shown in the study of these tetrahedrally bonded materials because of their wide optoelectronic, electro‐optic, and nonlinear device applications 5–7. The Hg‐related defect chalcopyrite compounds such as HgGa 2 S 4 and HgAl 2 Se 4 are getting more attention because of high nonlinear susceptibility, low absorption coefficient, and considerable birefringence 7.…”

“…Recently, a growing interest has been shown in the study of these tetrahedrally bonded materials because of their wide optoelectronic, electro‐optic, and nonlinear device applications 5–7. The Hg‐related defect chalcopyrite compounds such as HgGa 2 S 4 and HgAl 2 Se 4 are getting more attention because of high nonlinear susceptibility, low absorption coefficient, and considerable birefringence 7. Systematic studies on the variation of different thermophysical properties of defect chalcopyrite have gained considerable interest among solid‐state physicists.…”

“…The knowledge of thermal expansion behavior of the material is essential for analyzing the growth conditions of bulk single crystals of sufficient size and optical quality of melt 10. Many such fundamental properties for HgAl 2 Se 4 are not sufficiently evaluated due to experimental difficulties like oxygen affinity of Al and chemical reactivity of Hg 4–11 while single crystals of HgAl 2 Se 4 compound were first grown by Hahn et al 12.…”