Low current collapse and low leakage GaN MIS-HEMT using AlN/SiN as gate dielectric and passivation layer

An effective passivation and gate insulator with low current collapse and improved dynamic ON-state resistance (RON) for GaN MIS-HEMT is demonstrated in this work. The structure of passivation and gate insulator is fabricated by 4-nm SiN as the first passivation layer and 1-nm AlN. The bilayer AlN/SiN structure integrates the advantages of SiN and AlN. SiN passivation has been proved to effectively reduce GaN surface states. AlN has high bandgap of ∼6.2 eV which can suppress leakage current. Hence, the unfavorable effects such as trapping effect and leakage current which will induce current collapse and are effectively suppressed by using AlN/SiN bilayer thin film. A GaN MIS-HEMT with AlN/SiN passivation and gate dielectric exhibits improved I-V characteristics, low leakage current, low current collapse, and improved dynamic RON at high quiescent drain bias of 100 V.