Role of defects and phonons in bandgap dynamics of monolayer WS2 at high carrier densities
Abstract
We conduct ultrafast pump-probe spectroscopy in monolayer WS2 at high pump fluences to gain direct insight into interactions between a high density of carriers, defects, and phonons. We find that defects in the lattice play a major role in determining the relaxation dynamics by trapping the photoexcited carriers and acting as non-radiative recombination centers that emit phonons. In the high carrier density regime explored in our experiments, we observe substantial changes in the transient absorbance signal at unexpectedly long-time delays which we attribute to phonon-induced band gap modification. Our probe frequency dependent measurements and modeling indicate a renormalization of the bandgap by up to 23 meV. These results highlight the importance of defects and phonons for optical applications of monolayer transition metal dichalcogenides.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Dec 03, 2020
- Source ID
- 10.1088/2515-7639/abc13b
Entities
People
- Alexandra Brasington
- Arpit Dave
- Arvinder Sandhu
- Bin Chen
- Brian J LeRoy
- Dheeraj Golla
- John R. Schaibley
- Sefaattin Tongay
Organizations
- Air Force Office of Scientific Research
- Army Research Office
- Division of Electrical, Communications & Cyber Systems
- Division of Materials Research
- Division of Physics
- Science Foundation Arizona