ABSTRACT
There has been considerable interest over the last decade in the defects formed during the growth of diamond films using chemical vapor deposition (CVD). The synthesis of this promising engineering material by low-pressure methods has effectively developed into a rapidly expanding field during this period. The defects have been studied mainly by electron diffraction (ED) and high-resolution electron microscopy (HREM) techniques. A number of attempts at medium-high resolution to obtain information on the microstructure and on the nature of the defects have been reported, showing various types of morphology (1-8) and a wide variety of growth defects (9-23). Several HREM investigations of the defect structure have also been performed using microscopes with better point resolutions, up to 0.17-0.16 nm (24-39). The most striking feature observed in such films is the presence of multiple twinning on {111} planes. The twins are frequently present as large domains, the simplest interfaces corresponding to coherent first order (( 3) twinning. Higher-order interfaces (( 3n, n 2 to 4) can also be found, arising from the interaction of simpler configurations. Pentagonal arrangement of twins, twinning dislocations, stacking faults, and different types of associated dislocation have also been identified. Note that these defects, quite characteristic of diamond prepared by CVD, have very rarely been seen in natural diamond, where other types of defects are found, such as platelets (40-43), helical dislocations (44), or voidites (45-47).
