Ultrafast valley relaxation dynamics in single layer semiconductors

Andrew Barrette; Cong Mai; Yifei Yu; Yuriy Semenov; Zhenghe Jin; Ki Wook Kim; Linyou Cao; Kenan Gundogdu

doi:10.1117/12.2062401

5 September 2014 Ultrafast valley relaxation dynamics in single layer semiconductors

Andrew Barrette, Cong Mai, Yifei Yu, Yuriy Semenov, Zhenghe Jin, Ki Wook Kim, Linyou Cao, Kenan Gundogdu

Proceedings Volume 9198, Ultrafast Nonlinear Imaging and Spectroscopy II; 91980K (2014) https://doi.org/10.1117/12.2062401
Event: SPIE Optical Engineering + Applications, 2014, San Diego, California, United States

Abstract

Single layer transition metal dichalcogenides are 2D semiconducting systems with unique electronic band structure. Two-valley energy bands along with strong spin-orbital coupling lead to valley-dependent carrier spin polarization, which is the basis for recently proposed valleytronic applications. These systems also exhibit unusually strong many body effects, such as strong exciton and trion binding, due to reduced dielectric screening of Coulomb interactions. Not much is known about the impact of strong many particle correlations on spin and valley polarization dynamics. Here we report direct measurements of ultrafast valley specific relaxation dynamics in single layer MoS₂ and WS₂. We found that excitonic many body interactions significantly contribute to the relaxation process. Biexciton formation reveals hole valley/spin relaxation time in MoS₂. Our results suggest that initial fast intervalley electron scattering and electron spin relaxation leads to loss of valley polarization for holes through an electron-hole spin exchange mechanism in both MoS₂and WS₂.

Citation Download Citation

Andrew Barrette, Cong Mai, Yifei Yu, Yuriy Semenov, Zhenghe Jin, Ki Wook Kim, Linyou Cao, and Kenan Gundogdu "Ultrafast valley relaxation dynamics in single layer semiconductors", Proc. SPIE 9198, Ultrafast Nonlinear Imaging and Spectroscopy II, 91980K (5 September 2014); https://doi.org/10.1117/12.2062401

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available