Atomic Force Microscopy of (100), (110), and (111) Homoepitaxial Diamond Films

摘要

We present atomic force microscopy images of diamond films grown by chemicalvapor deposition epitaxially on diamond (100), (110), and (111) substrates. The films were grown from 0.2-1.6% mixtures of CH4 and C2H2 and H2 in a hot-filament reactor at a total pressure of 25 Torr. The substrate and filament temperatures were held at 810-1000 deg C and 2000-2150 deg C, respectively. A (100)-oriented diamond film grown with 0.3% CH4 at a substrate temperature of 810 deg C was rough on the micron scale, exhibiting pyramidal features, terraces, and penetration twins, while films grown at higher substrate temperatures and hydrocarbon flow rates were smooth on the nm scale and showed evidence of a (2x1) reconstruction. A (110)-oriented film was very rough on the micron scale but nearly atomically smooth on the 0.5-5nm scale and exhibited local slopes higher than 40 deg with no evidence of faceting. A film grown on a diamond (111) substrate underwent spontaneous fracture due to tensile stress and exhibited a roughness of =10-50 nm on the =100 nm lateral scale in regions far away from any cracks. The implications of the morphological features for diamond growth mechanisms are discussed.