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Structural Distortions and Energy Band Structure of Ag‐Doped As 2 S 3 and Ag 2 S 3
Author(s) -
Kaur Veerpal,
Tripathi Surya Kant,
Prakash Satya
Publication year - 2020
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.202000185
Subject(s) - band gap , monoclinic crystal system , density functional theory , lattice constant , doping , triclinic crystal system , crystallography , condensed matter physics , chemistry , electronic band structure , materials science , crystal structure , computational chemistry , physics , diffraction , optics
The density functional theory (DFT) with generalized gradient approximation (GGA) for exchange correlation potential as incorporated within SIESTA code is used to investigate the structural distortions and energy bands of Ag x As 2 – x S 3 ( x = 0–2). The lattice parameters and cell volume change asymmetrically with an increase in Ag concentration due to asymmetric changes in electrostatic and strain field interactions. The optimized lattice geometry of As 2 S 3 , Ag 1 As 1 S 3 , and Ag 2 S 3 is monoclinic, whereas for other configurations, it becomes triclinic. Unlike Ag 2 S 3 , the layering is not found in the structure of Ag 2 S 3 . The mobility gap decreases and then increases with an increase in Ag concentration. The minimum value of mobility gap is 0.04 eV for the configuration Ag 1 As 1 S 3 . The partial density of states (PDOS) of d orbital electrons significantly enhances with an increase in Ag concentration, and the structural changes in PDOS of s , p , and d orbital electrons suggest the weak and strong p – d hybridizations in valence and conduction bands, respectively. The reduction in the mobility gap suggests that Ag‐doped As 2 S 3 is more conducting than As 2 S 3 as observed experimentally.