Nanovideography of ultrafast charge carrier dynamics in van der Waals materials
- PC Department Online Seminar
- Date: Dec 6, 2021
- Time: 11:00
- Speaker: Dr. Markus Huber
- Universität Regensburg
In this talk, I will show how we use ultrafast scanning near-field optical microscopy to bypass this limitation and gain access to the transient, nanoscale dielectric functions of materials after photo-excitation by ultrashort laser pulses. We have applied this technique – simultaneously achieving a 10 nm spatial and 10 fs temporal resolution – to study carrier dynamics on their intrinsic length and time scales. I will focus on van-der-Waals bonded materials in this seminar which show great promise for future ultrathin electronics. We directly observed photo-activated surface polaritons in real space and traced their decay dynamics in black phosphorus. Using the tomographic sensitivity of the near fields, we extracted the surface dielectric function on the three-dimensional topological insulator (Bi0.5Sb0.5)2Te3. Recently, we introduced a new contact-free nanoscopy technique centered around probing the local polarizability of photogenerated electron–hole pairs with evanescent terahertz fields. This concept is capable of tracing ultrafast charge carrier dynamics even in insulating materials. Thus, we were able to observe the ultrafast tunneling of electron-hole pairs across two transition metal dichalcogenide monolayers with a temporal resolution faster than a single cycle of light.
Our results demonstrate the potential of this
technique for revealing how ultrafast charge dynamics governs the properties of
a large variety of solid-state systems.
Meeting-ID: 968 0911 9863