Interface control in hybrid superconductor-semiconductor heterostructures and devices

Precise control of dielectric-semiconductor and epitaxial metal-semiconductor interfaces is critical to the development of hybrid platforms intended to support topological superconductivity. In this talk I will describe efforts to tailor physical properties in epitaxial aluminum-indium arsenide structures while minimizing the deleterious impact of disorder. The two-dimensional electron gas (2DEG) residing in shallow InAs quantum wells coupled to epitaxial aluminum is a widely utilized platform for exploration of topological superconductivity. Strong Rasha spin-orbit coupling, a large effective g factor, and control over proximity-induced superconductivity are important attributes needed to support topological phases. We report on the transport properties of 2DEGs residing 10 nm below the surface in shallow InAs quantum wells in which mobility may exceed 100,000 cm^2/Vs at 2DEG density below 1x10¹²cm^-2. These heterostructures are fabricated into gate-defined arrays of nanowires and quantum dots used to probe topological superconductivity. These effecitively one dimensional channels are sensitive to multiple sources of disorder, both intrinsic in nature and some induced by fabricatoin. Specific disorder mechanisms impacting device performance will be discussed.