Comparison of the crystalline quality of homoepitaxially grown CVD diamond layer on cleaved and polished substrates

A transmission electron microscopy (TEM) study, comparing homoepitaxial diamond layers grown on different substrate surface preparation states and crystallographic orientation is presented. Quality of epilayers grown on {111} cleaved surface and on {001} polished one is evaluated in terms of crystalline defects. Focused ion beam (FIB-dual beam) sample preparations are observed by TEM using the {111}, {400} and {022} reflections of the [011] pole. Burgers vector analysis allowed to conclude the presence of 60 degrees dislocations oriented along all the different < 110 > directions in the cleaved sample, while no dislocations are observed on the polished one. A complete dislocation analysis is performed for that sample. The presence of dislocations in an undoped (i.e. fully lattice matched) epilayer is surprising; and is probably induced by atomic steps, generated by the cleavage process. This notes down the importance of the substrate if high quality diamond epilayers want to be grown. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim