Structural and Band Dispersion Analysis in Mixed-Metal Pyrite Dichalcogenides Cd_xZn_1-xTe₂: DFT Insights

This article uses first-principles DFT computations to present structural properties, electronic band structures and density of states (DOS) in II-(VI)<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> mixed-metal pyrite dichalcogenides Cd<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf>Zn<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</inf>Te<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>. A small modification in the crystal structure is observed and it changes from pure cubic to pseudo-cubic depending on the Cd-composition, x. Indirect-to-direct bandgap transition and the presence of double valleys in the conduction band in the electronic band structures are noticed for different Cd-compositions of the Cd<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf>Zn<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</inf>Te<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> mixed crystal system. Further, metal mixing causes enhancement of bandgap following a huge nonlinear pattern with negative bowing, which is normally unusual. However, high Te contribution is evident in the DOS across all mixing conditions. The flat conduction band profile along with direct bandgap and the high density of energy states lead to a broader absorption spectrum that suggests potential applications of the compounds in photovoltaic and optical devices. The DOS and structural parameters are used to explain the results obtained in the mixed-metal pyrite dichalcogenide Cd<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf>Zn<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</inf>Te<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>.