Abstract
Abstract The composition-engineered band structures of two-dimensional (2D) ternary transition-metal dichalcogenides (TMDCs) semiconductor alloys directly dominate their electronic and optical properties. Herein, in this paper, a detailed theoretical and experimental study on the composition-dependent nonlinear optical properties of 2D MoS x Se2−x alloys was carried out. The first-principles calculations were performed to investigate the compositionally modulated properties of monolayer 2D MoS x Se2−x (x = 0.25, 0.5, 1.0, 1.5, and 1.75) in terms of the carrier effective mass, carrier density and mobility, as well as band-gaps. Furthermore, high-quality few-layered MoS x Se2−x (x = 0.2, 0.5, 1.0, 1.5, and 1.8) nanosheets were fabricated by using liquid phase exfoliation method. The third-order nonlinear optical response was investigated by open-aperture Z-scan technique, revealing composition-dependent saturable absorption, and light modulation properties, which were correlated to the theoretical calculations and further confirmed by using MoS x Se2−x nanosheets as saturable absorbers (SAs) for all-solid-state pulsed lasers. In particular, a mode-locked solid-state laser with pulse width of 227 fs was realized with MoS0.2Se1.8 as SA, for the first time to our best knowledge. Our work not only provides a comprehensive understanding of the compositionally and defectively modulated nonlinear optical responses of ternary TMDCs alloys, but also paves a way for the development of 2D materials-based novel optoelectronic devices.
Highlights
Low-dimensional nanomaterials exhibit unique physical and chemical properties and functions that much differ from their bulk counterparts due to the quantum confinement effect
transition-metal dichalcogenides (TMDCs) semiconductors were discovered following behind graphene and have been regarded as the outstanding representative 2D materials because of their exotic and promising properties, including tunable band gap transiting from indirect of bulk to direct of monolayer, moderate carrier mobility, good bendability, and strong nonlinear optical response, making them to be exciting lowdimensional semiconductors for the new generation of electronic and photonic devices
Our results provide a promising solution for the development of 2D TMDCs material-based electronic and photonic devices with desirable properties
Summary
Low-dimensional nanomaterials exhibit unique physical and chemical properties and functions that much differ from their bulk counterparts due to the quantum confinement effect. In the past two decades, numerous efforts from both theories and experiments have been devoted to explore different kinds and properties of 2D layered materials [4,5,6,7]. TMDCs semiconductors were discovered following behind graphene and have been regarded as the outstanding representative 2D materials because of their exotic and promising properties, including tunable band gap transiting from indirect of bulk to direct of monolayer, moderate carrier mobility, good bendability, and strong nonlinear optical response, making them to be exciting lowdimensional semiconductors for the new generation of electronic and photonic devices.
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