BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Science and Math//NONSGML Events//EN CALSCALE:GREGORIAN X-WR-CALNAME:Science and Math - Events X-ORIGINAL-URL: X-WR-CALDESC:Science and Math - Events BEGIN:VEVENT UID:20190911T0756Z-1568188564.8232-EO-21315-1@ STATUS:CONFIRMED DTSTAMP:20191016T131506Z CREATED:20190911T075539Z LAST-MODIFIED:20190911T075703Z DTSTART;TZID=Asia/Singapore:20190920T110000 DTEND;TZID=Asia/Singapore:20190920T123000 SUMMARY: Goki Eda (National University of Singapore) – Van der Waals semico nductor optoelectronics DESCRIPTION: Two-dimensional (2D) van der Waals semiconductors such as mono layer MoS2 and WSe2 are an attractive building block for novel photonic dev ices due to their strongly excitonic character. X-ALT-DESC;FMTTYPE=text/html:


Two-dimensional (2D) van der Waals semiconductors such as monolayer MoS2 and WSe2 are an attractive building block for novel photonic devices due to their strongly excitonic c haracter. Monolayer transition metal dichalcogenides exhibit strong exciton ic absorption due to band nesting [1] and allow exploration of hybrid quasi -particle states such as plexcitons [2] through strong dipole-dipole coupli ng [3]. The first part of this talk will focus on their approaches to reali zing electrical generation\, manipulation\, and detection of excitons and t heir complexes based on various van der Waal heterostructures. Specifically \, he will discuss how MIS-type heterostructures allow electrically tunable excitonic electroluminescence [4] and electro-optic upconversion in linear optics regime. They demonstrate that hexagonal boron nitride can serve as a unipolar tunnel barrier that allows hot carrier injection and energy harv esting. Their results reveal that interlayer charge transfer dynamics is tu nable with electrical bias and competes with thermalization of hot photocar riers leading to distinct optoelectronic response at high photon energy exc itation. The second part will discuss their recent discovery of a novel mon olayer MoS2 growth mechanism based on vapor-liquid-solid conversion [5]. Th ey show that alkali metal plays a key role in reducing the melting point of the precursors and triggering the vapor-liquid-solid mode\, yielding epita xial growth of monolayer nanoribbons.


  1. D. Kozawa et al. “Photocarrier relaxation pat hway in two-dimensional semiconducting transition metal dichalcogenides” Nat. Comm. 5\, 4543 (2014).
  2. W. Zhao et al. “Exciton -plasmon coupling and electromagnetically induced transparency in monolayer semiconductors hybridized with Ag nanoparticles” Adv. Mater. 28\, 2709 (2016).
  3. D. Kozawa et al. "Efficient interlayer energy transfe r via 2D dipole coupling in MoSe2/WS2 heterostructures" Nano Lett. 16\, 408 7 (2016).
  4. S. Wang et al. “Efficient carrier-to-exciton con version in field emission tunnel diodes based on MIS-type van der Waals het erostack” Nano Lett. 17\, 5156 (2017).
  5. S. Li\, et al.< /em> “Vapor-liquid-solid growth of monolayer MoS2 nanoribbons” Nat. Mat er. 17\, 535 (2018).

Speaker's Bio

Dr. Eda received his M.Sc. in Materials Science and Engineering from Worces ter Polytechnic Institute in 2006 and Ph.D. in the same discipline from Rut gers University in 2009. He became a Newton International Fellow of the Roy al Society of the UK and worked at Imperial College London. Dr. Eda joined the National University of Singapore as an Assistant Professor of Physics a nd Chemistry\, and a member of the Centre for Advanced 2D Materials (CA2DM) in 2011. He is a recipient of the Singapore National Research Foundation ( NRF) Research Fellowship and many awards including the Singapore National A cademy of Science (SNAS) Young Scientist Award\, University Young Researche r Award\, and IPS Omicron Nanotechnology Award. He is an Associate Editor o f npj 2D Materials and Applications. He also formerly served as an Editoria l Board Member for Scientific Reports. Dr. Eda investigates a wide range of condensed matter physical properties of two-dimensional (2D) materials. Hi s research focuses on the extraordinary photophysical properties of atomica lly thin van der Waals compounds and their potential applications in novel photonic devices. He has co-authored > 100 peer-reviewed papers including 7 invited review/perspective articles and a book chapter. His work has been cited over 29\,000 times (h-index of 51) as of Jan 2019.

CATEGORIES:SMT Research Seminar Series,Special Seminars LOCATION:SUTD Think Tank 11 (Building 1\, Level 5) GEO:1.340219;103.962443 ORGANIZER;CN="SUTDPillarAdministrator" URL;VALUE=URI: r-series/goki-eda-national-university-of-singapore-van-der-waals-semiconduc tor-optoelectronics/ ATTACH;FMTTYPE=image/png: END:VEVENT BEGIN:VTIMEZONE TZID:Asia/Singapore BEGIN:STANDARD TZOFFSETFROM:+0800 TZOFFSETTO:+0800 DTSTART:20190321T150000 TZNAME:SGT END:STANDARD END:VTIMEZONE END:VCALENDAR