Ohmic Conacts to p-GaN on the Basis of Carbon Nanomaterials

We have designed and verified a new structure for ohmic contacts to p-GaN based on a layer of carbon nanotubes (CNT), reduced graphene oxide (r-GO) and metallic layers of Cr, Pd and Au, namely in configurations Au/Cr/r-GO/CNT/p-GaN and Au/Pd/r-GO/CNT/p-GaN. The effects have been studied of the annealing temperature and the gas ambient upon the electrical properties of the contacts. Annealing of the Au/Pd/r-GO/CNT/p-GaN structure in air at 500°C for 1 minute resulted in linear I - V curves measured between planar electrodes on the p-GaN. Hence, addition of r-GO to the CNT interlayer between p-GaN and the metallization layer is a highly promising procedure for further improvements of the ohmic contacts to p-GaN.