NANOMETER-SCALE MORPHOLOGY OF HOMOEPITAXIAL DIAMOND FILMS BY ATOMIC FORCE MICROSCOPY

We present the first atomic force microscopy images of diamond films grown homoepitaxially in a hot filament reactor on (100), (111), and (110) natural diamond substrates. (100)-oriented diamond films grown with 0.3% CH4 at a substrate temperature of 810-degrees-C were rough on the micron scale, exhibiting pyramidal features and penetration twins, while films grown with 1.6% CH4 at 1000-degrees-C were nearly atomically smooth and showed evidence of a (2 X 1) reconstruction. A (111)-oriented film cracked due to tensile stress and was rough on the 50-500 nm scale, while a (110)-oriented film was rough on the micron scale but nearly atomically smooth on the 0.5-5 nm scale. Implications of the observed morphologies for diamond growth mechanisms are discussed.