Ionizing beam-induced adhesion enhancement and interface chemistry for Au-GaAs

Abstract

MeV ion beam-induced adhesion enhancement of Au-films (∼500 Å thick) on p-type and n-type GaAs substrates has been studied by the scratch test, ESCA, and nuclear reaction hydrogen profiling. For films resistively deposited in a diffusion pumped chamber at 2−5×10^(−6)torr, the data indicate that the adhesion enhancement is associated with oxide layers on the substrate surface adsorbed before the film deposition. The ESCA data suggest that water vapour dissociates and forms Ga(OH)_3 at the interface layers under ionizing radiation. The oxide concentration at the interface varies with substrate electronic properties and gives a large difference in the adhesion enhancement. However, the data obtained so far on the hydrogen concentration at the interface indicate that within our range of sensitivity it is about the same for substrates with different electronic properties. Our data demonstrate the importance of a thin absorbed (impurity) layer for the interface chemistry and adhesion enhancement by ionizing radiation.

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