Improved DC performance and current stability of ultrathin-Al ₂ O ₃ /InAlN/GaN MOS-HEMTs with post-metallization-annealing process

Abstract 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-Al ₂ O ₃ , by focusing on the Al ₂ O ₃ /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 ( R _sh ), and the current collapse evaluated by pulsed I – V characteristics was effectively suppressed, because of the reduction in the electronic states at the Al ₂ O ₃ /InAlN interface. Transmission electron microscope analysis of the Al ₂ O ₃ /InAlN structures revealed that the bond disorder at the Al ₂ O ₃ /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 Al ₂ O ₃ /InAlN interface, leading to the improved DC performance and current stability for the Al ₂ O ₃ /InAlN/GaN MOS-HEMTs.