题目：Luminescence Mechanisms of Two-dimensional WS₂ Monolayers

 

Two-dimensional (2D) transition metal dichalcogenides (2D-TMDs) are quickly emerging as a new kind of electronic and optoelectronic materials with great application potential in different areas after the discovery of carbon-based 2D material-graphene. Unlike graphene, 2D-TMDs monolayers have a direct band gap within the visible spectral region, which offers a great opportunity to explore semiconductor optical physics in the 2D limit. Recent theoretical study predicts diverse excitonic states and many-body effects in 2D-TMDs [1]. In this talk, we will report an in-depth micro-photoluminescence study of luminescence mechanisms of 2D WS₂ monolayers prepared in two different approaches. At room temperature, two distinctive emission peaks at 2.017 eV and about 1.955 eV have been identified to be from the fundamental band-edge excitonic transition and the many-body transition, respectively [2]. Detailed spectral data and arguments will be presented in the talk.  

 

[1] D. Y. Qiu, F. H. da Jornada, and S. G. Louie, Phys. Rev. Lett., 2013, 111, 216805.

[2] X. H. Wang, et al, to be published.

 

SJ Xu received his PhD degree in Electronic Engineering from Xi'an Jiaotong University in 1993 under the supervision of Prof. Jinsheng Luo. Currently he is a professor with tenure in Department of Physics, The University of Hong Kong (HKU). Prior to joining HKU faculty, he worked in Institute of Materials Research and Engineering, Singapore as research fellow, in National University of Singapore as NSTB postdoctoral fellow with Prof. Soo-Jin Chua, and in Institute of Semiconductors, CAS as a postdoc with Prof. Hou-Zhi Zheng. SJ Xu has already published >130 scientific articles with SCI citation times >2600. The Hirsch-index is 26. His current research interests include optoelectronic physics and related phenomena in new and traditional semiconductors as well as their optoelectronic device structures. He was the recipient of Research Collaborative Award (Fund) of NSFC for Overseas Chinese, Hong Kong and Macau Scholars in 2010 (formerly known as Outstanding Young Investigator Award for Overseas Chinese, Hong Kong and Macau Scholars).

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