Fig. 2From: AlN Surface Passivation of GaN-Based High Electron Mobility Transistors by Plasma-Enhanced Atomic Layer Deposition a Refractive index as a function of the wavelength. b XPS depth profiles of the AlN films grown by N2 (closed square) and NH3 (open circle) ambient plasma. The ALD-AlN was grown on Si(100) substrateBack to article page