Ab Initio Study on Stability, Electronic and Optical Properties of Monolayer Mo<sub>1−x</sub>W<sub>x</sub>Se<sub>2</sub> Alloys
Sheikh Mohd. Ta-Seen Afrid, Swagata Goswami Utsha, Ahmed Zubair
Abstract
Due to their unique structures and physical properties, monolayer transition metal dichalcogenides (TMDs) have gained attention in nanoelectronic and flexible device applications. We investigated the effect of alloying on stability, electronic and optical properties of two–dimensional TMD alloys by exploring Mo <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1−x</inf> W <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> Se <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> . Using density–functional theory (DFT) calculations, we evaluated geometrical structures, electronic band structures, the contributions from atomic orbitals in both valence and conduction bands, Bader charge analysis, effective mass, mobility, dynamic stability, dielectric functions, and absorption coefficient for varying compositions in Mo <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1−x</inf> W <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> Se <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> alloy. Our investigation revealed that the direct band gap in these alloys could be modulated with nonlinear dependency on composition. The effective mass and mobility of both hole and electron can be varied notably for different composition of alloys. Mo <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1−x</inf> W <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> Se <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> alloys were energetically and dynamically stable. Furthermore, the high optical absorption of the alloys can be utilized in optoelectronic devices. The findings of this study enlighten the tunable electronic and optical properties of TMD alloys that will be beneficial for designing nanophotonic and nanoelectronic devices.