The Nature And Origin Of {113} Faults In Irradiated Silicon And Germanium

Abstract

SUMMARY At elevated temperatures, electron irradiation damage in silicon and germanium forms faulted defects on {113} which are elongated in <110>. During the present work on silicon, these {113} faults were observed to unfault, apparently by glide, to give elongated interstitial loops with b = a /2<110>. Since the tetrahedral interstitial sites between adjacent {113}s form a full {113}, in both number and distribution, it was concluded that the atoms were accommodated in these positions. A fault of this type comprises interstitial pairs, the atoms of which are on adjacent tetrahedral sites a /4<111> apart, and it is proposed that these already exist, or are formed, when a fault nucleates. Two‘di‐interstitials’ then close‐pack along one of the three <110>s normal to their <111> axis, thus nucleating a {112} loop. This is unable to grow in any direction other than <110>, because its habit plane is occupied by matrix atoms, so the loops become extended. The defect grows in width by nucleating further loops on {112} planes, extended parallel to the first, and the‘array’ forms an elongated {113} defect, on a plane 10° from the original {112}. This gives the observed faulted {113} loops, elongated in <110>, with R ≃/11<113>.