Tomography of Transport Pathways in Selective-Area-Grown Nanowires Using Angle-Resolved Conductance Fluctuations

Abstract

Understanding the spatial distribution of carriers is important for interpreting transport in nanoscale devices. Here, we apply conductance fluctuation tomography to planar selective-area-grown InAs nanowires in both normal-normal and normal-superconductor device geometries. By tracking the evolution of conductance-interference features as a function of magnetic-field strength and orientation, we extract information about the geometry of phase-coherent transport pathways. Using theory to distinguish between bulk-dominated transport, coherent near-surface transport across facets, and transport confined to individual facets. The measurements are consistent with transport dominated by a near-surface accumulation layer in InAs. Devices with normal contacts show behavior consistent with coherent transport across the nanowire apex, whereas hybrid normal-superconductor devices exhibit signatures of more facet-dependent transport. These results demonstrate how universal conductance fluctuations can be used as a tomographic probe of phase-coherent transport pathways in semiconductor nanostructures.