Precipitation of Group V Elements and Ge in SiO sub 2 and Their Drift in a Temperature Gradient

It is shown that P, Sb, and Ge ions implanted in SiO sub 2, precipitate into spherical clusters of up to a 1000angstroms, when heat treated in an oxygen-free ambient. This behavior is similar to that reported earlier for As implants. The clusters can be detected directly by transmission electron microscopy, or inferred from the unidirectional drift of the doped zone in a temperature gradient. Boron, a representative of group III, is the only element among those tested that does not migrate in a gradient T, indicating the absence of phase separation.