Preparation of Ohmic contacts to GaAs/AlGaAs-core/shell-nanowires.

Ohmic contacts to GaAs/AlGaAs core/shell nanowires are prepared by using a Ni/AuGe/Ni/Au layer system. In contrast to Ohmic contacts to planar GaAs/AlGaAs layer systems here, relatively low alloying temperatures are used in cylindrical geometry. Lowest resistances are found for annealing temperatures of 320 °C and 340 °C. For annealing temperatures exceeding 360 °C, the nanowires degraded completely. Nanowires annealed under optimized conditions preserved their Ohmic characteristics even down to temperatures of 4 K. [ABSTRACT FROM AUTHOR]