Experimental investigation of the channel network formed by high-dose He implantation

A buried 5 μm thick He depth distribution plateau was implanted into Al at RT together with two well separated mono-energetic peaks on it as markers. The variation of implanted profile versus implanted dose was measured in-situ by 3500 keV RBS, confirming that even at the onset of exfoliation (8.33x1018 He/cm2) there was no channel network interconnecting all of the implanted depth region. During further bombardment, together with the appearance of surface deformation, more and more He originating from large cracks under the detached layer were released through the cracks and ruptures of the cover. The cracks resulting from the surface deformation appeared at the two separated maxima of the He depth profile. (orig.)