Bachelor's defense: Weiyuan Chen

Title: Pb etchant development towards Pb-based quantum device fabrication

Abstract

Semiconductors-superconductors hybrid materials are mainly studied for their potential application for topological quantum computing. Majorana zero modes found in these heterostructure systems could be used to create more stable qubits, thus leading to scalable quantum computers. To realize these heterostructures, improvements to material quality and fabrication processes are needed. Samples of hybrids based on Pb as the superconductor and InAs and InSb as the semiconductor were etched with MF321. MF321 proved to be an effective etchant for Pb. The optimal etching time should at least be 60s. The best method to achieve an uniform etch was by shaking. AFM, SEM and EDS were used to characterize the etched samples. Atomic steps matching the lattice constant of InAs were found in AFM. SEM and EDS data showed no signals of Pb supporting the claim that MF321 could etch Pb.