Mapping of electrostatic potentials within core-shell nanowires by electron holography

Phase profiles within core-shell nanowires composed of intrinsic germanium cores and shells of germanium oxide and/or doped germanium were imaged using electron holography in a transmission electron microscope. Accurate mean inner potentials for germanium and its oxide were determined from phase data obtained from experimental electron holography with knowledge of the thickness profile of the nanowire. Using measured and simulated phase profiles, it was possible to determine the dopant concentration within a shell of doped germanium around an intrinsic germanium core. Measurement of mean inner potentials and dopant levels within semiconductor core-shell nanowires was demonstrated.