Defect structures of homoepitaxial diamond grown on various sites studied by transmission electron microscopy

Defect structures in a homoepitaxial diamond film grown by chemical vapor deposition (CVD) have been observed by cross-sectional transmission electron microscopy (XTEM). It was found that the homoepitaxial diamond still contains stacking faults and twins, especially in the interfacial regions grown on the (1(1) over bar1$) facet and the (1(1) over bar0$) edge, while dislocations are dominant in the upper regions. On the (001) face, however, the film does not contain such common defects, but does contain similar to <112>-aligned rows of interstitial dislocation loops with deformed configurations, indicative of defect decomposition from helical dislocations as a result of supersaturation of point defects. The density of these latter defects decreased in regions grown on the middle of the substrate. Many interstitial dislocation loops were also discerned lying in the (001) interface. Analytical electron microscopy (AEM) showed the presence of Fe and Si impurities only at the interface. The possible origins of the defects are discussed.