  We show that a thin film of a three-dimensional topological insulator (3DTI)
with an exchange field is a realization of the famous Haldane model for quantum
Hall effect (QHE) without Landau levels. The exchange field plays the role of
staggered fluxes on the honeycomb lattice, and the hybridization gap of the
surface states is equivalent to alternating on-site energies on the AB
sublattices. A peculiar phase diagram for the QHE is predicted in 3DTI thin
films under an applied magnetic field, which is quite different from that
either in traditional QHE systems or in graphene.
