High-quality β-(Al x Ga 1− x ) 2 O 3 thin films on sapphire substrates by face-to-face annealing

High-quality β-(Al 0.68 Ga 0.32 ) 2 O 3 (288 arcsec) films have been fabricated through face-to-face annealing on a sapphire substrate which is covered with epitaxial Ga 2 O 3 .