Advanced Methods of Semiconductor Research Seminar – Tuesday 3rd of June 2025
We cordially invite you to Advanced Methods of Semiconductor Research Seminar on Tuesday 3rd of June 2025 at 13:15 in room 321, building A-1, where there will be delivered a lecture:
Growth mechanisms and properties of GaN nanowires crystallized by Plasma-Assisted MBE
by Dr. Marta Sobańska
from Institute of Physics, Polish Academy of Sciences in Warsaw
Lecture abstract:
Group III-nitride semiconductors in a form of nanowires (NW) demonstrate enhanced physical, electrical, and optical characteristics compared to their bulk counterparts. They possess a high surface-to-volume ratio, enhanced mechanical strength, catalytic activity, the ability to accommodate significant strain, as well as the potential for miniaturization of devices and components. Therefore, NWs attracted great interest for basic research and for device applications.
The aim of this talk is to present our results on mechanisms active during plasma-assisted MBE (PAMBE) growth of GaN NWs and their impact on properties of such nanostructures. I will start with the most popular case of self-assembled formation of GaN NWs on amorphous substrates. A specifically attractive benefit offered by such system is the possibility of creating vertically well aligned and single-crystalline NWs which are not epitaxially linked to the substrate. Optical and electronic properties of such NWs will be presented. In particular, the problem of mixed polarity inside NW ensemble will be addressed.
In the second part, I will focus on formation of GaN NWs on metals – the case when the NWs are strongly epitaxially linked to the substrate, so their orientation is determined by crystallographic orientation of the substrate. I will show that due to unidirectional supply of atoms in MBE, device relevant arrays of vertical GaN NWs can be obtained on polycrystalline metallic substrates despite epitaxial link of GaN to randomly oriented substrate grains. Electrical characteristics and polarity of such NW will be discussed. Finally, I will show examples of selective area growth of GaN NWs, both in self-assembled as well as in GaN-on-GaN epitaxy growth mode, that allow controlling spatial arrangement of the NWs on the substrate.
