Formation of axial metal–semiconductor junctions in GaAs nanowires by thermal annealing

We demonstrate the formation of nanoscale axial Schottky contacts in GaAs nanowires by thermal annealing of NiGeAu multilayers. Energy dispersive x-ray spectroscopy indicates that in specific annealing conditions a sharply-defined Au-rich phase can be obtained in the vicinity of the metallic contacts. Charge transport characteristics are analyzed for different degrees of diffusion of the Au-rich phase in the wire and indicate that it has a metallic nature. The mechanism behind this local post-growth modification of the nanowire composition and its potential impact on device applications are discussed. (paper)