Student: Sreekumar Sreehari
Supervisor: Doc. Mgr. Martin Setvín, Ph.D.
Status: Assigned
Abstract:
From a classical point of view, electrons and holes added to a semiconductor behave as delocalized plane waves. In ionic lattices, strong electrostatic interactions result in a spatial confinement of the charge carrier or its complete localization. The resulting quasiparticle is called a polaron [1] and it has wide impact on applications. It can slow down charge transport and spoil the efficiency of photocatalytic or electrocatalytic devices. On the other hand, polarons stand behind exotic materials properties such as the colossal magnetoresistance or high-temperature superconductivity.
The focus of this Thesis is to develop a methodology for imaging and tracking polarons in real space. This approach is fundamentally novel: Other works always investigate polarons indirectly through the macroscopic materials properties. The combined scanning tunnelling microscopy/atomic force microscopy (STM/AFM) [2] technique principally allows the detection of a single polaron in real space, thanks to measuring its electrostatic forces. A possible ability to track such a polaron would allow obtaining full information about this quasiparticle. This Thesis is focused on investigating fundamental properties of polarons, as well as their influence on electronic properties and surface chemistry [3,4]. The experimental efforts will be mainly focused on surfaces of metal oxides.