GaN planar schottky barrier diode with cut-off frequency of 627 GHz

GaN Schottky barrier diodes(SBD) have shown great potential for high temperature, high power and high frequency applications. This paper presents the design, fabrication and measurement of the GaN planar SBD using the air-birdge Technology and electroplating Technology to reduce the parasitic parameters. An ohmic contact resistance of 0.15 Ω·mm was obtained with a Ti/Al/Ni/Au metal stack which is about 40% lower than a Ti/Al/Ti/Au metal stack. Also, we found the chemical treatment of the N+ GaN surfaces employing HCl+HF was better than BOE. Devices with various anode diameters(3–7μm) were fabricated on the same chip. The fabricated GaN SBD diodes were characterized by I-V and C-V measurements at DC. On-wafer small-signal S-parameter measurements were also performed up to 50 GHz. A cut-off frequency (fc) of 627 GHz was achieved for GaN planar SBD with 7 μm anode diameter.