A route for reliable conductive scanning probe characterization of FIB machined ZnO nanopillars

Zinc oxide structures with size in the micro and nano-scale range represent key candidates for developing novel, cheap and efficient electronic devices, power generators and sensors based on the cooperative response of a large number of synced structures. The accurate electrical characterization of single ZnO micro/nanostructures is thus critical for assessing and optimizing the device performance and reliability, and requires the use of metallic scanning nano-probes for establishing electrical contact with the nano-structures. We report on the characterization of the contact resistance between AFM conductive tip and a selection of metallic layers to be used as top metallic coating allowing for nano-electrical characterization of FIB machined ZnO micro/nanopillars. Our findings show that the use of an Au film on top of Ti ohmic contact layer is crucial for reliable conductive AFM investigation of single isolated ZnO micro and nano-structures.