Experimental Physics/Electron- and Ion-Nanooptics
Organization name Institute of Optics and Atomic Physics
Office ER 1-1
Building ER
Room ER 297
Address Sekr. ER 1-1, Straße des 17. Juni 135
10623 Berlin

My name is Santiago Koloffon and I am doing my bachelor thesis in the AG Lehmann.

In my bachelor thesis we are concerned with the measurement of electrostatic potentials and fields in semiconductor nanostructures using a transmission electron microscope (TEM). Specifically, I measure the current generated by scanning a sample with an electron beam. In this process, the high-energy electron beam creates electron-hole pairs in the sample. Electric fields in the space charge region of a pn junction separate electrons and holes and a current flow is measurable. Depending on how the sample is switched and what voltage is applied (biasing), the electrons and holes are attracted to the contacts of the sample. This measurement method is called electron beam induced current (EBIC).

From this, we can map the variation and strength of the electric field of the pn junction. We then compare this with a potential profile from measurements using the electron holography method to better understand the advantages and disadvantages of the individual methods and to create a quantitative measurement method for determining pn junctions.

This topic, especially the STEBIC method, is still quite unexplored and relevant to current research. The group has very modern and capable equipment and is tackling interesting topics, for example, to develop new semiconductor technologies. This is very important for the production of new electronic and digital devices. I found these facts very attractive and convinced me to do my bachelor thesis in this group.