  A thin film of a topological insulator (TI) on a dielectric substrate and a
bulk TI - dielectric film - bulk TI structure are considered as natural
double-well heterostructures suitable for realizing the counterflow
superconductivity. The effect is connected with pairing of electrons and holes
belonging to different surfaces of TI and the transition of a gas of
electron-hole pairs into a superfluid state. The case of TI heterostructures
subjected to a strong perpendicular magnetic field is considered. It is shown
that such systems are characterized by two critical temperatures - a mean-field
temperature of pairing and a much smaller temperature of the superfluid
transition. The dependence of the critical temperatures on the magnetic field
is computed. The advantages of TI based structures in comparison with GaAs
heterostructures as well as graphene based heterostructures are discussed.
