Defects in synthetic diamond epitaxial layers were studied using transmission electron microscopy and high-resolution electron microscopy. Coherent twinning on {111} planes was found to be the dominant defect in chemically vapour deposited diamond thin films. High-resolution electron microscopic images revealed areas which exhibited a threefold periodicity due to overlapping Σ = 3 twins. The Σ = 9 interfaces which were present when two of these second-order twins overlapped were also observed. High-resolution electron microscopic images of a 60°, as well as of a pure screw, ribbon viewed along the direction of the ribbon permitted the determination of the stacking-fault energy in diamond, yielding a mean value of 209mJ/m2. This was significantly smaller than previously determined values, based upon the application of the weak-beam method to ribbons parallel to the foil. Atomic-scale models were proposed for a number of complex defect configurations which were observed in the diamond epitaxial layers: twinning dislocations, interactions between stacking faults and interactions between a stacking-fault and a twin interface.

Electron Microscopy Study of Defects in Synthetic Diamond Layers. W.Luyten, G.Van Tendeloo, S.Amelinckx, J.L.Collins: Philosophical Magazine A, 1992, 66[6], 899-915