Junction phenomena for unconventional semiconductors

We consider polaronic effects at the FET junctions based on molecular crystals or conducting polymers. In the molecular crystal, Coulomb interaction of free electrons with surface polar phonons of the dielectric layer results in the formation of a long-range surface polaron. The effect is strongly enhanced by the bias electric field. For the junction with conducting polymers, new allowed electronic bands appear inside the band gap instead of the usual band bending. The bias electric field and the injected charge penetrate into the polymer via creation of the soliton lattice which period changes with the distance from the contact surface. For an isotropic material, we estimate conditions for the injected charge to be captured in a close proximity to the junction surface thus providing a high efficiency for the possible dielectrics–metal transition.