Understanding the ultrafast carrier dynamics and the mechanism of two-dimensional(2D)transition metal dichalcogenides(TMDs)is key to their applications in the field of optoelectronic devices.In this work,a single puls...Understanding the ultrafast carrier dynamics and the mechanism of two-dimensional(2D)transition metal dichalcogenides(TMDs)is key to their applications in the field of optoelectronic devices.In this work,a single pulse pump probe method is introduced to detect the layer-dependent ultrafast carrier dynamics of monolayer and few-layer WS_(2) excited by a femtosecond pulse.Results show that the ultrafast carrier dynamics of the layered WS_(2) films can be divided into three stages:the fast photoexcitation phase with the characteristic time of 2–4 ps,the fast decay phase with the characteristic time of 4–20 ps,and the slow decay phase lasting several hundred picoseconds.Moreover,the layer dependency of the characteristic time of each stage has been observed,and the corresponding mechanism of free carrier dynamics has been discussed.It has been observed as well that the monolayer WS_(2) exhibits a unique rising time of carriers after photoexcitation.The proposed method can be expected to be an effective approach for studying the dynamics of the photoexcited carriers in 2D TMDs.Our results provide a comprehensive understanding of the photoexcited carrier dynamics of layered WS_(2),which is essential for its application in optoelectronics and photovoltaic devices.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 51975232 and 51727809)the Experiment Center for Advanced Manufacturing and Technology in the School of Mechanical Science & Engineering of HUST for the technical support.
文摘Understanding the ultrafast carrier dynamics and the mechanism of two-dimensional(2D)transition metal dichalcogenides(TMDs)is key to their applications in the field of optoelectronic devices.In this work,a single pulse pump probe method is introduced to detect the layer-dependent ultrafast carrier dynamics of monolayer and few-layer WS_(2) excited by a femtosecond pulse.Results show that the ultrafast carrier dynamics of the layered WS_(2) films can be divided into three stages:the fast photoexcitation phase with the characteristic time of 2–4 ps,the fast decay phase with the characteristic time of 4–20 ps,and the slow decay phase lasting several hundred picoseconds.Moreover,the layer dependency of the characteristic time of each stage has been observed,and the corresponding mechanism of free carrier dynamics has been discussed.It has been observed as well that the monolayer WS_(2) exhibits a unique rising time of carriers after photoexcitation.The proposed method can be expected to be an effective approach for studying the dynamics of the photoexcited carriers in 2D TMDs.Our results provide a comprehensive understanding of the photoexcited carrier dynamics of layered WS_(2),which is essential for its application in optoelectronics and photovoltaic devices.
