Formation of interstitial-type dislocation loops in tetrahedral semiconductors by precipitation of vacancies

Abstract

It is hypothesized that when vacancies precipitate to form voids in tetrahedral semiconductors, e.g., Si and GaAs, reconstruction reactions occur on the internal surfaces of these voids in the same manner as they are observed to occur on external surfaces of the same crystallographic orientation. Previously, it has been concluded that many of the various reconstruction reactions observed on various semiconductor surfaces produce hillocks by expelling a portion of the atoms from the unreconstructed (ideal) surface to migrate in a reaction front across the surface. From these two lemmas, it is here concluded that the corresponding waves of atoms driven by reconstruction on internal surfaces will precipitate into pillars of crystal-line material within the void and produce dislocation loops at which the lattice planes bow away from the center. Such dislocations are conventionally denoted "interstitial type." This mechanism may explain several observations of "interstitial type" dislocations in semiconductors, including Si and GaAs, for which there is much evidence for vacancies and no other evidence for self-interstitials. © 1978 The American Physical Society.