Using a new facility for microscopic and ion-accelerator investigation of materials, an in situ TEM study was made of the effects of helium implantation on a tri-layer system consisting of monocrystalline silicon (c-Si), silicon dioxide and polycrystalline silicon (poly-Si). Co-irradiation of these components enabled direct comparisons to be made of differences between the response of c-Si and poly-Si to He irradiation; in particular, differences in the development of interstitial clusters and bubbles and eventual amorphisation. For implantation to high fluences (>1017 ions/cm2), very significant levels of porosity were observed to build up in the Si, leading to changes in the width of the Si layers of up to 29% Although no helium bubbles were formed in the SiO2 layer, a very significant dimensional change (but in this case an observed shrinkage) also occurred in this material. Finally, room temperature amorphisation of the Si was observed at high fluences, beginning at somewhat lower fluences in the poly-Si than in the c-Si.

An in situ TEM Study of the Effects of 6keV He Ion Irradiation on Si and SiO2. S.E.Donnelly, J.A.Hinks, C.J.Pawley, K.J.Abrams, J.A.van den Berg: Journal of Physics - Conference Series, 2012, 371[1], 012045