  Hydrogenated diamond has been regarded as a promising material in electronic
device applications, especially in field-effect transistors (FETs). However,
the quality of diamond hydrogenation has not yet been established, nor has the
specific orientation that would provide the optimum hydrogen coverage. In
addition, most theoretical work in the literature use models with 100%
hydrogenated diamond surfaces to study electronic properties, which is far from
the experimentally observed hydrogen coverage. In this work, we have carried
out a detailed study using fully atomistic reactive molecular dynamics (MD)
simulations on low indices diamond surfaces i.e. (001), (013), (110), (113) and
(111) to evaluate the quality and hydrogenation thresholds on different diamond
surfaces and their possible effects on electronic properties. Our simulation
results indicate that the 100% surface hydrogenation in these surfaces is hard
to achieve because of the steric repulsion between the terminated hydrogen
atoms. Among all the considered surfaces, the (001), (110), and (113) surfaces
incorporate a larger number of hydrogen atoms and passivate the surface
dangling bonds. Our results on hydrogen stability also suggest that these
surfaces with optimum hydrogen coverage are robust under extreme conditions and
could provide homogeneous p-type surface conductivity in the diamond surfaces,
a key requirement for high-field, high-frequency device applications.
