Attosecond charge carrier dynamics at nanoscale interfaces

• Applicant: Dr. Jan Vogelsang
• Subject Area: Experimental Condensed Matter Physics ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 462448709

Semiconductors form the basis of today’s technological development. They enabled the rapid improvement of digital information processing, which in principle is used by every branch of research: be it the recording of measurement data, the evaluation, the modeling or the publication of the knowledge gained. Also the increasing networking of society and the availability of information are fundamentally changing our behavior, for example in the dissemination of opinions and democratic decision-making. Above all, our society will change permanently by the possibilities that the increasing availability of information and its automated evaluation brings with it. As explosively as the applicability of digital technologies is developing, so are the performance requirements for data processing systems. A considerable part of the electrical energy converted worldwide is already used to transport electrons through semiconductors for information processing. Progressive miniaturization of semiconductor components resulted in significant energy savings and an increase in the frequency of switching cycles. Switching frequencies in the range of 100 GHz are possible today, but this is more than an order of magnitude higher than the switching rates actually achieved in today's processors. The reason for this is that the capacity of the interconnects, which are required to control the transistors, does not allow charging times far below a nanosecond. It is therefore obvious to first optimize the signal feed line by using new technologies before the transistors themselves are redesigned. This project aims at laying the foundation for such a technological step in signal transport in semiconductor nanostructures. The aim is to make ultrafast currents, driven by strong optical fields in the PHz range, visible and controllable in semiconductor nanostructures. To this end, a new realm of simultaneously high spatial and temporal resolution will be explored: The shortest light pulses in the range of attoseconds are combined with electron microscopy in order to follow ultrafast processes on their natural nanometer-small spatial scale. The short flashes of light ensure that the movements of the charge carriers are frozen so that an electron microscope can take a picture of the current state with its high resolution. This prevents the movement from being smeared out and fundamental knowledge about the optically driven electron transport on the nanoscale can be obtained.

• DFG Programme: Independent Junior Research Groups
• Major Instrumentation: Femtosekunden Lasersystem ; ToF-Photoemissions-Elektronenmikroskop
• Instrumentation Group: 5130 Sonstige spezielle Elektronenmikroskope ; 5700 Festkörper-Laser