X-ray topography was used to study single crystal diamond samples homo-epitaxially grown by microwave plasma-assisted chemical vapour deposition (CVD) on high-pressure high-temperature and CVD synthetic diamond substrates. Clusters of dislocations in the CVD diamond layers emanated from points at or near the interface with the substrate. The Burgers vectors of observed dislocations were determined from sets of {111} projection topographs. Dislocations have line directions close to the [001] growth direction and were either edge or 45° mixed dislocations. Where groups of dislocations originated at isolated points they tended to be of the edge variety. Where the substrate surface was deliberately damaged before growth, two sets of dislocations were observed to have propagated from each line of damage and there was a tendency for dislocations to be of the 45° mixed variety with a component of their Burgers vector parallel to the polishing direction. It was demonstrated that X-ray topography could be used to deduce the growth history of CVD synthetic diamond samples produced in multiple growth stages.

X-ray Topography Studies of Dislocations in Single Crystal CVD Diamond. M.P.Gaukroger, P.M.Martineau, M.J.Crowder, I.Friel, S.D.Williams, D.J.Twitchen: Diamond and Related Materials, 2008, 17[3], 262-9