It was recalled that the bombardment of hydrogenated amorphous material with MeV ions led to the formation of H molecules, within the sample, in the region where they originally bonded. This effect was experimentally detected here by using double-layer structures which consisted of plasma-deposited hydrogenated and deuterated amorphous Si-C alloys having various C contents. This effect was simultaneously used to study the low-temperature transport of H molecules through this type of material. It was deduced that, at temperatures below the temperature for the onset of thermal desorption, H molecules could migrate through material with a C content of 20mol%, and escape. At lower C-contents, the formation of molecules within the material eventually resulted in morphological damage to the films. The results indicated that, for H-loss during annealing at lower temperatures, the rate-limiting step was the formation of molecules within the material. The observation of an isotope effect in the extent of ion beam-induced H desorption led to the modification of an existing model for this process.

Hydrogen Loss in a-Si:C:H Layers Induced by MeV Ion Beam Irradiation E.H.C.Ullersma, P.Ullersma, F.H.P.M.Habraken: Physical Review B, 2000, 61[15], 10133-41