  We calculate the dilepton emissions as the decay product of the charm and
bottom quarks produced in heavy-ion collisions at RHIC energy. We take into
account the next-to-leading-order radiative corrections in perturbative QCD to
the heavy quark production from both an initial hard parton-parton scattering
and an ideal quark-gluon plasma. We find that the thermal charm decay dominates
the dilepton production in the low dilepton mass region ($<2$ GeV), while the
heavy quark production from the initial scattering takes over the intermediate
and high mass regions ($> 2$ GeV). Our result also indicates the importance of
the bottom quark in the high mass region ($>4 $ GeV ) due to its large mass and
cascade decay. If the initial scattering produced charm suffers a significant
energy loss due to the secondary interaction, the bottom decay constitutes the
major background for the thermal dileptons.
