A Novel Regrown Ohmic Contact Technique to Improve the Performance of GaN HEMT

A novel regrown ohmic contact technique is proposed to improve the performance of GaN HEMT by decreasing the parasitic resistance, which features regrowth of n
⁺
GaN without any mask on the whole wafer and self-stopping etching of the n
⁺
GaN on the access region. Compared with the reference HEMT, this regrown HEMT demonstrates improved on-state performance with increased output current density as well as peak extrinsic transconductance and reduced knee voltage. In addition, the off-state characteristics and gate diode characteristics have not been significantly affected by the self-stopping etching. Both good on-state and off-state characteristics can contribute to a high RF power performance.