THERMAL CHEMICAL VAPOR-DEPOSITION OF HOMOEPITAXIAL DIAMOND - DEPENDENCE OF SURFACE-MORPHOLOGY AND DEFECT STRUCTURE ON SUBSTRATE ORIENTATION

The crystallographic anisotropy in chemical vapour deposition diamond growth has been investigated by the homoepitaxial deposition of diamond layers on substrates of different orientations. The films were grown in a hot filament reactor. Diamond plates parallel to and 4-degrees misoriented from {111}, {100} and {110}, as well as a hemispherically shaped diamond were used as substrates. Optical and scanning electron microscopy demonstrated that the surface morphology and thus the mechanism of diamond formation is strongly orientation dependent. Shallow growth hillocks, indicative of step growth, were found on the {111} and {100} faces. The plates slightly misoriented from these two low index directions are covered by surface dendrites, bunch patterns and macrosteps. The other orientations, including {110}, are rough and show features characteristic of S or K faces. The F character of {100} suggests the occurrence of (2 x 1) surface reconstruction during crystal growth. Cathodoluminescence topography and spectroscopy proved that the crystallographic orientation of the growing surface also plays a main role in the formation of point defects.