Improved DC performance and current stability of ultrathin-Al2O3/InAlN/GaN MOS-HEMTs with post-metallization-annealing process

We evaluated the effect of the post-metallization-annealing (PMA) process on drain current stability of InAlN/GaN metal-oxide-semiconductor high electron mobility transistors (MOS-HEMTs) with a 1 nm thick ultrathin-Al2O3, by focusing on the Al2O3/InAlN interface properties. We clarified that the improvement in DC characteristics (drain current, on-state resistance, and transconductance) with PMA was attributed to the decrease in sheet resistance (Rsh), and the current collapse evaluated by pulsed I-V characteristics was effectively suppressed, because of the reduction in the electronic states at the Al2O3/InAlN interface. Transmission electron microscope analysis of the Al2O3/InAlN structures revealed that the bond disorder at the Al2O3/InAlN interface was significantly recovered after PMA. It is considered that the PMA process is effective in enhancing the relaxation of dangling bonds and/or point defects at the Al2O3/InAlN interface, leading to the improved DC performance and current stability for the Al2O3/InAlN/GaN MOS-HEMTs.