The correlation of residual contamination with void formation at the contact/SiO2 interface for single GaN NW devices was investigated. The morphology at the metal/SiO2 interface was observed by removing the annealed Ni/Au films from the SiO2 with carbon tape, which was then mounted and imaged by the use of scanning electron microscopy (SEM). Void formation at the metal/SiO2 interface, which can negatively affect device performance, is shown to occur during the annealing of Ni/Au contacts to NWs on SiO2. It was discovered that residual contamination from the NW solution and photolithography on the NW-SiO2 surface during metal deposition can significantly increase the amount of void formation at the metal/SiO2 interface and that predeposition cleaning reduces the amount of void formation that is associated with the residual contamination. Different cleaning methods were investigated in order to minimize the amount of void formation. The degree of void formation at the metal/SiO2 interface is used to evaluate the effectiveness of the different cleaning methods. The most effective method for removing residual contamination from the NW-SiO2 surface was a UV ozone treatment followed by a dilute HCl bath prior to contact deposition.
Citation: Journal of Nanoscience and Nanotechnology
Pub Type: Journals
residual contamination, void formation, cleaning methods