Bulletin of the American Physical Society
2015 Annual Meeting of the APS Mid-Atlantic Section
Volume 60, Number 14
Friday–Sunday, October 23–25, 2015; Morgantown, West Virginia
Session B4: Optical Characterization of Low Dimensional System I |
Hide Abstracts |
Chair: Pavel Borisov, West Virginia University Room: Waterfront Hotel Salon E |
Saturday, October 24, 2015 3:30PM - 4:06PM |
B4.00001: TBD Invited Speaker: Hrvoje Petek . [Preview Abstract] |
Saturday, October 24, 2015 4:06PM - 4:18PM |
B4.00002: Ultrafast Spectroscopy of Exciton and Exciton Dynamics in Few and Monolayer Flakes of WS$_{\mathrm{2}}$. Sudiksha Khadka, Shrouq Aleithan, Max Livshits, Jeffery Rack, Martin Kordesch, Eric Stinaff Single layer of Transitional metal dichalcogenides (MX$_{\mathrm{2}})$ are 2D semiconductor that has a direct band gap in visible spectrum and possesses a strong spin-orbit interaction along with broken inversion symmetry in crystal structure. Thus they have possible application in optoelectronic devices, photovoltaics and photodetection, molecular sensing, 'valleytronics', and flexible transparent electronics. Tungsten Disulphide (WS$_{\mathrm{2}})$, one of the member of MX$_{\mathrm{2}}$ family, has a direct band gap of 2.2 eV and a large valley splitting of about 0.4 eV. This leads to the existence of two distinct and direct excitons A and B. Here, we present a detailed study of exciton states and their decay mechanisms in mono and few layer WS$_{\mathrm{2}}$ using femto-second transient absorption spectroscopy. We report a new peak in its differential absorption spectra at 3.01\textpm 0.1 eV whose origin in k space is under further investigation. The exponential fitting of decay curve of the exciton A reveals three time components as 1.7\textpm 0.3 ps, 33.5\textpm 10 ps and 670\textpm 15 ps, most likely corresponding to carrier-carrier scattering, carrier-phonon scattering, and radiative relaxation respectively. [Preview Abstract] |
Saturday, October 24, 2015 4:18PM - 4:30PM |
B4.00003: Importance of Interfacial Dephasing in Plasmonic Resonant Energy and Hot Carrier Transfer Scott Cushing, Alan Bristow, Nianqiang Wu The tunable absorption and scattering cross section of plasmonics has made it ideal for enhancing solar energy conversion. The plasmon can increase photoconversion in a semiconductor by trapping light through multiple reflections, transferring the hot electron and holes from the metal to the semiconductor, or exciting interband transitions in the semiconductor by resonant energy transfer. The enhancement mechanisms have so far been understood in terms of the plasmon's resonance energy and hot spots, considering the semiconductor and plasmon as separate systems. Herein, we use a combination of transient absorption spectroscopy, action spectrum photocatalysis, and a density matrix model to show the effects of interfacial dephasing and coupling between the plasmon and semiconductor must also be included to explain the currently lower than predicted performance of plasmonic devices [1]. Accounting for these effects, how efficient plasmonic solar energy conversion can be obtained will also be discussed. \newline [1] Li et al, Nat. Photonics 9, 601 (2015) [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700