Structural features of Σ = 19, [110] GaAs tilt grain boundaries

Abstract

Σ = 19, [110] tilt grain boundaries have been observed to facet parallel to particular planes; the facets lie along \({\left\langle {\bar 33\bar 1} \right\rangle }\)A/\({\left\langle {3\bar 3\bar 1} \right\rangle }\)B, (\({\bar 558}\))A/\({7\bar 74}\))B and (\({\bar 22\bar 7}\))A/(\({4\bar 45}\))B. The structural unit of the Σ = 19 (\({\bar 33\bar 1}\))A/(\({3\bar 3\bar 1}\))B [110] boundaries consists of 5- and 7-member rings, which are similar to the core structure of a/2[110] edge dislocations. The polarities in each grain on either side of the boundaries has been confirmed by CBED methods; a lower number of anti-site type cross-boundary bonds occur along the boundaries compared to when the polarity of one grain is reversed. The presence of 7-member rings and anti-site cross-boundary bonds results in a more open atomic structure at the boundary, shortening the distance between the first and the second {331} atomic planes from the boundary plane by 40%.