  The problem of a size quantization for charge carriers in a planar quantum
well consisting of different monolayers of transition metal dichalcogenides is
solved using the Dirac model and the four-band model. For excitons, bound
states of electrons and holes at the size quantization levels in such a quantum
well, the energy spectrum was found in two cases: the Bohr radius is much
smaller than the width of the quantum well (dielectric permeability of a
substrate is relatively small) and the Bohr radius is much larger than it (the
case of a strong dielectric screening). It is shown that the energy spectrum in
these two cases is completely different. A method for the synthesis of the
heterostructures under consideration is also proposed.
