Improved fmax and breakdown voltage in AlGaN/GaN HEMT with plasma treatment

Abstract

A combination of high maximum oscillation frequency (f max ) and breakdown voltage (V br ) was achieved in AlGaN/GaN high electron mobility transistors (HEMTs) with N 2 O plasma treatment on the access region. Compared with the non-treated HEMTs, the gate leakage current is nearly reduced three orders of magnitude due to the formation of oxide layer in the gate region. A suppressed current collapse and effective gate length extension is obtained due to plasma treatment on the gate-source and gate-drain regions. The passivation effect is closely matched with the conventional SiN passivation method, meanwhile it can avoid introducing additional parasitic capacitance due to thinner thickness. The small signal measurement shows that 90-nm gate length HEMT can yield f T and f max of 98 and 322GHz, respectively. The HEMT with plasma treatment can simultaneously obtain high f max and breakdown voltage, and exhibits a record f max ·V br of 25THz·V.