Surface passivation process for GaN-based electronic devices utilizing ECR-CVD SiNx film

Surface passivation process of GaN utilizing electron-cyclotron-resonance ( ECR) excited plasma has been characterized and optimized for realization of stable operation in GaN-based high-power/high-frequency electronic devices . From XPS analysis, the NH4OH treatment as well as the ECR-N-2 and ECR-H-2 plasma treatments were found to be effective in removing natural oxide and contaminants from the GaN surface. The SiNx/GaN structure prepared by the ECR excited plasma chemical vapor deposition (ECR-CVD) process showed bette r C-V behavior compared to the SiO2/GaN structure. Surface treatment proces s using the ECR plasma improved interface properties and achieved the Dit v alue of 2 x 10(11) cm(-2) eV(-1) or less. An estimate of the valence band o ffset by XPS showed that the present SiNx/n-GaN structure has a type-I band lineup, suitable for the surface passivation of GaN-based devices. No pron ounced stress remained at the SiNx/GaN interface, which was confirmed by Ra man spectroscopy.