Suppression of Andreev reflection mediated transport by diffuse boundary scattering

In systems consisting of strings of superconducting dots deposited on wet etched InAs/GaSb heterostructure wires we have observed a severe suppression of Andreev reflection mediated transport in the region of small bias. This effect can be attributed to diffuse boundary scattering from the edges of the wires and shows expected enhancements as the wires are made narrower and/or a magnetic field is applied perpendicular to the plane of the wires; both leading to an increase in boundary scattering. The length scales that govern this phenomenon appear consistent with experimental findings.