Engel-Vosko GGA Approach Within DFT Investigations of the Optoelectronic Structure of the Metal Chalcogenide Semiconductor CsAgGa2Se4

作者：Azam Sikander; Khan Saleem Ayaz; Goumri Said Souraya

来源：Journal of Electronic Materials, 2016, 45(1): 746-754.

DOI：10.1007/s11664-015-4192-8

• Chalcogenides
• electronic structure
• optical spectra
• EV-GGA

Metal chalcogenide semiconductors have a significant role in the development of materials for energy and nanotechnology applications. First principle calculations were applied on CsAgGa2Se4 to investigate its optoelectronic structure and bonding characteristics, using the full-potential linear augmented plane wave method within the framework of generalized gradient approximations (GGA) and Engel-Vosko GGA functionals (EV-GGA). The band structure from EV-GGA shows that the valence band maximum and conduction band minimum are situated at I" with a band gap value of 2.15 eV. A mixture of orbitals from Ag 4p (6)/4d (10), Se 3d (10), Ga 4p (1), Se 4p (4) , and Ga 4s (2) states have a primary role to lead to a semiconducting character of the present chalcogenide. The charge density iso-surface shows a strong covalent bonding between Ag-Se and Ga-Se atoms. The imaginary part of dielectric constant reveals that the threshold (first optical critical point) energy of dielectric function occurs 2.15 eV. It is obvious that with a direct large band gap and large absorption coefficient, CsAgGa2Se4 might be considered a potential material for photovoltaic applications.