  3He atoms dissolved in superfluid 4He may form dimers (3He)2 in
two-dimensional geometries. We study dimer formation in films of dilute 3He-4He
mixture. After designing a schematic 3He-3He interaction potential we calculate
the dimer binding energy for various substrates. It is shown that 3He impurity
states localized near the substrate give rise to the largest magnitudes of the
binding energies.
