PhD Defense: Filip Krížek

Semiconductor nanowire networks grown by Molecular Beam Epitaxy: Vapor-Liquid-Solid and Selective Area Growth

This project presents advances in in-situ III-V semiconductor nanowire network growth by Molecular Beam Epitaxy. 
The first part is dedicated to the Vapor-Liquid-Solid mechanism and growth of nanocrosses in free-standing geometry. Three novel types of nanocrosses are introduced and characterized with respect to their crystal structure and transport properties. Fist type is grown based on understanding of nanowire nucleation on (001) substrates and provides an interesting multi-terminal geometry with embedded crystal phase quantum dots within the junctions. The two other types are based on control over in-situ change of nanowire growth direction and form single crystalline junctions. 
New results in Selective Area Growth of in-plane nanowire networks are introduced in the second part. It is demonstrated that the Selective Area Growth offers full scalability into large quasi 1-D networks, that is comparable to standard top-down methods. In addition, it offers the possibility of electronic device fabrication directly on the growth chip. We show, that the presented networks satisfy the basic requirements set for material systems proposed to host Majorana quasiparticles and provide an interesting platform for experiments related to topological quantum computing.