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 °C were rough on the micron scale, exhibiting pyramidal features and penetration twins, while films grown with 1.6% CH4 at 1000 °C were nearly atomically smooth and showed evidence of a (2×1) 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.