Talk "Monolayer semiconductors: new exciton physics and devices"

When: 08.08.2023 13.00-14.00 h
Where: Seminar Room PI4 (4-319, Pfaffenwaldring 57)

Excitons in 2D monolayer semiconductors have attracted a great deal of attention in recent years due to many unique properties. These unique properties make 2D materials both an ideal platform for the study of fundamental physics and interesting material basis for potential new device applications. In this talk, we will present some of the recent results of our group on optical study of the 2D materials, especially on new aspects of exciton physics 3,4,6 and potential device application of 2D materials as optical gain materials for nanoscale lasers.  These include optical gain due to co-existence and mutual conversion of excitons, trions, and electrons/holes in a gated structure. Our focus will be on the recent experimental observation of a series of new spectral peaks that are not attributable to excitons, trions, or bi-excitons. Our combined theory and experiments6 provide strong evidence for the existence of a new four-particle entity, the quadruplon which corresponds to an irreducible cluster of two electrons and two holes. Details of theory and experimental evidences will be discussed.