Fabrication and improved performance of AlGaN/GaN HEMTs with regrown ohmic contacts and passivation-first process

Paper in proceeding, 2016

This work reports the fabrication of AlGaN/GaN HEMTs with regrown ohmic contacts using either a passivation-last or a passivation-first process, where the order of surface passivation and gate metallization processes is different. An improved performance is demonstrated using the passivation-first process, achieving a maximum current/power gain cutoff frequency (fT/fmax) around 60/127 GHz with an 80-nm gate length. The ohmic contacts were regrown with highly doped n-GaN, resulting in a contact resistance of ~0.2 Ω·mm. The RF performance can be further enhanced by reducing the extrinsic gate capacitance and short channel effects.