Masters Defense: Asbjørn Drachmann

Proximitizing InAs 2DEG with NbTi through Epitaxial Aluminum

I will present work on realizing and characterizing transparent coupling between the superconductor NbTi and an InAs two dimensional electron gas (2DEG).
As an introduction I will review the many benefits of realizing transparent hybrids of 2DEGs and conventional high temperature superconductors, followed by fundamental theory on superconductors, 2DEGs and their superconducting proximity effect.
An explanation of our material system and a walk-through of the fabrication will be given together with information on the electrical circuits used for measurements.
I will present measurements of two sub-micron sized devices made from the same NbTi deposition: a superconductor-quantum point contact-2DEG device and a superconductor-2DEG-superconductor Josephson junction.
Both devices show induced superconductivity in the 2DEG from the NbTi with close to perfect transmission, and their results are comparable.