HRTEM INSITU OBSERVATION OF GRAIN BOUNDARY MIGRATION OF SILICON Σ BOUNDARY AND ITS STRUCTURAL TRANSFORMATION AT 1000K

Abstract
The atomic process of both the grain boundary migration and the structure transformation of (111)A/BΣ3 and (112)A/BΣ3 CSL boundaries in silicon was investigated in-situ by the HRTEM at 1000K. A unit distance of the boundary migration was not one plane distance. It coincided with the CSL lattice constant ; The boundary migrated not by successive replacement of atoms of the next plane but by the exchange of atomic site from that of one crystal to the other's in the volume which corresponds to a unit CSL cell next to the boundary. Owing to the coincidence of the unit migration distance with the period of the CSL neither the strain in the vicinity nor the disturbance of periodicity in the neighboring (112)A/BΣ3 boundary resulted by the migration. A non periodic (112)A/BΣ3 boundary changed during heating into a periodic one at around 950K. Both periodic and non periodic structures appeared in turn when the temperature was kept at 1000K.