2025/06/02 by Kevin Ndang Amassa, Jean-Pierre Tchapet Njafa, Amassa, Kevin Ndang +7
Engineering · Materials Science · Physics and Astronomy · #Chalcogenide Semiconductor Thin Films #2D Materials and Applications #Semiconductor materials and interfaces
paper · pdf · doi:10.48550/arxiv.2506.01464
This study presents a comprehensive first-principles investigation of the structural, electronic and optical properties of monolayer \chMo1-xWxS2 alloys, systematically exploring the full compositional range (x=0 to 1) using density functional theory (DFT). We establish that these alloys are thermodynamically stable and maintain the characteristic 2H crystal structure with minimal structural perturbation upon alloying. A key finding is the preservation of a direct bandgap at the K-point across all compositions. This gap exhibits continuous tunability, increasing near-monotonically from \SI1.696\electronvolt (\chMoS2) to \SI1.858\electronvolt (\chWS2), a critical feature for tailoring optoelectronic devices. Electronic structure analysis reveals the systematic evolution of the orbital contributions of transition metal d and sulfur p at the edges of the band with composition. Consequently, the optical spectra, evaluated up to \SI8\electronvolt, show a progressive blueshift in the main features of the interband transition with increasing \chW content, accompanied by predictable changes in key optical constants. Our comprehensive results validate the monolayer \chMo1-x WxS2 as an electronically versatile platform that offers fine control over electronic and optical properties via alloying, making these tunable direct-gap semiconductors highly promising for next-generation photodetectors, light emitters, and potentially flexible optoelectronic applications exploiting their 2D nature.