  We analyze numerically the radiation and channeling properties of
ultrarelativistic electrons and positrons propagating through a periodically
bent diamond crystal grown on a straight single-crystal diamond substrate. Such
systems can be called hetero-crystals and they are one of the experimentally
realized samples for the implementation of crystalline undulators. We state
that in such systems the channeling and radiation properties of projectiles are
sensitive to the projectile particles energy as well as on the beam propagation
direction, i.e. on whether the beam of particles enters the crystal from the
side of substrate or from the side of periodically bent crystal. The
predictions made are important for design and practical realization of new
crystalline undulators.
