Atomic diffusion bonding with oxide underlayers using Al and amorphous Si films for high optical density applications

Atomic diffusion bonding with oxide underlayers using Al and a-Si films was examined to create a bonded interface with Al 2 O 3 and Si-oxides having large band gaps for high optical density applications. Surface free energy of the bonded interface greater than 2 J m −2 and 100% light transmittance were achieved after annealing at 300 °C in the range of film thicknesses δ on both sides from 0.3 to 0.5 nm using Al films and with δ of around 0.5 nm using a-Si films. Structural analyses revealed that the bonded interface consists of Al 2 O 3 and Si-oxides with oxygen dissociated from oxide underlayers.