[19a-Z33-1~12] 21.1 Joint Session K "Wide bandgap oxide semiconductor materials and devices"

[19a-Z33-6] Post-deposition annealing effect on ALD-Al₂O₃ formed on (001) β-Ga₂O₃

〇Atsushi Hiraiwa^1,4, Kiyotaka Horikawa², Hiroshi Kawarada^1,2,3, Motohisa Kado⁵, Katsunori Danno⁵ (1.RONLI, Waseda Univ., 2.FSE, Waseda Univ., 3.KMLMST, Waseda Univ., 4.IMaSS, Nagoya Univ., 5.Toyota Motor Corp.)

Keywords:Al2O3, atomic layer deposition, annealing

Post-deposition annealing (PDA) of atomic-layer-deposited (ALD) Al₂O₃ films formed on (001) β-Ga₂O₃ exacerbates the bias instability (BI) of the ALD-Al₂O₃/(001) β-Ga₂O₃ capacitors, in a non-monotonic way with PDA temperature. This result makes a stark contrast with that from capacitors that are similarly formed on GaN substrates, where BI was reduced monotonously with PDA temperature. Similar to the GaN capacitors, the leakage current in the (001) β-Ga₂O₃ capacitors was reduced sharply by the crystallization of the ALD-Al₂O₃ film, but the threshold temperature for the current reduction was approximately 100ºC lower than that for the GaN capacitors. A space-charge-controlled field emission analysis revealed that this current reduction was mostly caused by the increase in the barrier height against the electron emission from the substrate.