The layers of carbon nanomaterials as the base of ohmic contacts to p-GaN

We have examined new structures for ohmic contacts to p-GaN, mainly for applications in light emitting devices, based on a layer of single-walled carbon nanotubes (SWCNT) and metallic layers of Au/Cr, Au/Ni-Mg(-O) namely in configurations Au/Cr/SWCT/p-GaN and Au/Ni-Mg(-O)/SWCT/p-GaN. The layer of carbon nanotubes was deposited on p-GaN by spraying a solution of synthesized SWCTs, the layers of Au/Cr were vapor deposited and the layers of Au/Ni-Mg(-O) were deposited by DC reactive magnetron sputtering in an atmosphere with and without a low concentration of oxygen (approx. 0.2 at%). It has been found that the contact structures provide a low resistivity ohmic contact after subsequent annealing in N2 ambient at 700 °C for 1 min. It has also been found that the structure containing the SWCNT interlayer exhibits lower values of contact resistance in comparison with an otherwise identical contact without the SWCNT interlayer.