Comparison of the crystalline quality of homoepitaxially grown CVD diamond layer on cleaved and polished substrates
Résumé
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 (FIBdual 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.