Figure 3

Microscope photographs of surface morphology. Microscope photographs of surface morphology of Ti/Al/Ta/Au (20/80/40/100 nm) ohmic stacks with different SiN_x thicknesses after annealing at 850°C for 30 s: (a) with 50-nm SiN_x encapsulation layer, (b) 100-nm SiN_x encapsulation layer, (c) 150-nm SiN_x encapsulation layer, and (d) 200-nm SiN_x encapsulation layer.