Ultrafast Dynamics in Bulk and Monolayer MoS$_{2}$ Measured with Femtosecond Pump-Probe Technique

POSTER

Abstract

MoS$_{2}$ is a typical material of transition-metal dichalcogenide family. It exhibits unique properties when thickness reduces to monolayer. Recent studies have shown strong photoluminescence (PL) and high carrier mobility on monolayer MoS$_{2}$, which makes it a promising candidate for future photonic and field-effect transistor (FET) applications. Our ultrafast measurement utilizes optical 400nm-pump 800nm-probe spectroscopy to reveal the relaxation dynamics of photo-excited carriers in both bulk and monolayer MoS$_{2}$. Measurement is carried out at ambient pressure for different pump fluences. Both a fast and a slow carrier lifetime are acquired in monolayer MoS$_{2}$ due to different carrier scattering mechanism. Carrier lifetimes are measured at different pump fluences, from which we propose possible carrier relaxation mechanisms. In suspended bulk MoS$_{2}$, coherent acoustic phonons with a peak frequency around 38GHz are observed. Phonon lifetime and amplitude at different pump fluences have also been investigated.

Authors

  • Xianghai Meng

    • Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712

  • Wenzhi Wu

    • Department of Electrical Engineering, Heilongjiang University, China

  • Avinash Nayak

    • Department of Electrical and Computer Engineering, The University of Texas at Austin, TX 78712

  • Jung-Fu Lin

    • Department of Geological Sciences, The University of Texas at Austin, Austin, TX 78712
    • Department of Geological Sciences, The University Of Texas at Austin

  • Deji Akinwande

    • Microelectronics Research Center, The University of Texas at Austin, Texas 78758, USA
    • The University of Texas at Austin
    • Univ of Texas, Austin
    • Department of Electrical and Computer Engineering, The University of Texas at Austin, TX 78712
    • UT Austin

  • Yaguo Wang

    • University of Texas System
    • Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712