Research Seminar - Maximilian Huber & Naoki Higashitarumizu

May 14, 2024
Maximilian Huber, Ph.D. Student, Lanzara’s Group & Naoki Higashitarumizu, Postdoctoral Researcher, Javey's Group

"Ultrafast control of the electronic structure of TiSe2 with light"

Abstract: "TiSe2 is an intriguing charge density wave (CDW) material, featuring a complex interplay of many-body interactions such as electron-electron, electron-lattice and electron-hole. By using time and angle resolved photoelectron spectroscopy (trARPES) we show how optical excitation can be used as a tool to precisely control its electronic structure. While weak excitation slightly perturbs the CDW gap, strong excitation drives a semimetallic state that cannot be observed under equilibrium conditions. This state appears on the ultrafast timescale (<50fs) and is characterized by a drastic band renormalization. With the aid of DFT+U calculations we are able to show that the creation of this non-equilibrium semimetallic state is driven by screening effects."

Large-scale processing of narrow bandgap 2D semiconductors for mid-infrared optoelectronics

Abstract: High-efficiency mid-wavelength infrared (λ=3–5µm) optoelectronics, including light emitters and photodetectors, are attractive for spectroscopy, night vision, biomedical imaging, and gas sensing. Recently, narrow bandgap 2D semiconductors such as black phosphorus and its alloys have attracted substantial interest in mid-infrared device applications surpassing the performance of conventional III-V and II-VI semiconductors of similar bandgap. However, achieving their scalable thin film which is optically active in mid-infrared has been challenging. In this talk, I will show methodologies to utilize these materials for large-scale optoelectronic applications.