Fabrication of a wider bandgap θ-Al₂O₃ by oxidation of ultrathin AlN films for leakage current reduction

Aluminum oxide (Al 2 O 3 ) films were fabricated through the oxidation of ultrathin aluminum nitride (AlN) films. The fabricated films exhibited a leakage current reduction compared to that of conventional Al 2 O 3 films fabricated using atomic layer deposition. This reduction in the leakage current can be attributed to the formation of θ -Al 2 O 3 , which has a wider-bandgap than γ -Al 2 O 3 . The formation of θ -Al 2 O 3 was attributed to the residual stress caused by the oxidation of the AlN thin films.