Comparison of surface passivation on films for reduction of current collapse in AlGaN/GaN high electron mobility transistors

Three different passivation layers (SiN/sub x/, MgO and Sc/sub 2/O/sub 3/) were examined for their effectiveness in mitigating surface-state-induced current collapse in AlGaN/GaN high electron mobility transistors (HEMTs). The plasma-enhanced chemical vapor deposited SiN/sub x/ produced /spl sim/80-85% recovery of the drain-source current, independent of whether SiH/sub 4//NH/sub 3/ or SiD/sub 4//ND/sub 3/ plasma chemistries were employed. Both the Sc/sub 2/O/sub 3/ and MgO produced essentially complete recovery of the current in GaN-cap HEMT structures and /spl sim/80-95% recovery in AlGaN-cap structures. The Sc/sub 2/O/sub 3/ had superior long-term stability, with no change in HEMT behavior over 5 months aging.