GRAIN-BOUNDARY DISLOCATIONS IN A SIGMA-13 GRAIN-BOUNDARY IN SILICON .1. ANALYSIS OF THE POSSIBLE GRAIN-BOUNDARY STRUCTURES AND DISLOCATIONS

The purpose of this paper is to describe the different grain boundary structures and kinds of dislocations which can arise in the {510} Sigm a 13 grain boundary in diamond cubic materials. Firstly, the different possible grain boundary structures are derived within the framework o f group theory, and then general expressions for the Burgers vectors o f the grain boundary dislocations which separate these structures are obtained. These grain boundary dislocations are of three kinds: (1)per fect grain boundary dislocations (also called DSC dislocations), which do not change the grain boundary structure, (2) imperfect grain bound ary dislocations, which relate different, but equivalent, grain bounda ry structures, and finally (3) partial dislocations, which separate tw o non-equivalent grain boundary structures. Transmission electron micr oscopy is then used to show that imperfect dislocations are indeed pre sent in a Sigma 13 (22.6 degrees/[001](1/2)) grain boundary in Si, and have Burgers vectors consistent with 1/4[001](1/2).