Ohmic contacts to p-GaP/n-ZnO core/shell nanowires based on Au metallization

This paper presents the technology of ohmic contacts to p-GaP/n-ZnO core/shell nanowires (NW) that have a radial pn heterojunction. To separately contact the GaP core and ZnO shell of an individual NW is not trivial as it requires two different types of ohmic metallization alloyed at different temperatures. The NWs were contacted using electron beam lithography and a lift-off technique in a two-step process: (1) the ZnO shell layer was removed from one NW end to reveal the GaP core onto which an Au/Zn alloy was deposited to contact GaP, (2) an Au/Al alloy was used to make contact to the ZnO shell layer.