Physics Bldg. Library, Rm. 223A
Condensed Matter - Biological Physics - Electrical & Computer Engineering Seminar presents Prof. Shiyuan Gao, Washington University, St. Louis, "Understanding Excitons in 2D Materials and Van der Waals Heterostructures from First-Principles," Wednesday, January 24, 2018 at 4:00 p.m.
Dr. Gao writes,
"Two-dimensional materials and their heterostructures have attracted much interest recently as promising candidates for photonics, optoelectronics, and valleytronics devices, where excitons dominate the optical properties. In this talk, I will first briefly review the theoretical efforts that went into understanding excitons in two-dimensional materials, focusing on the first-principles GW+BSE method. Then I will discuss a particular system of great experimental interest, the bilayer transition metal dichalcogenide heterostructure. Due to the interlayer coupling, the dipole oscillator strength and radiative lifetime of the low energy excitons in such bilayer heterostructure can be tuned by over an order of magnitude with an external gate field. I'll show a simple model that captures the essential physics behind this tunability and allows the extension of the first-principles results to arbitrary external gate fields."