LOCAL OPTICAL OSCILLATIONS NEAR A PLANE D EFECT IN SEMICONDUCTORS ANDDIELECTRICS

The theory of local optical oscillations near a plane defect is built for semiconductors and dielectrics with an ionic crystal lattice. It i s shown that, begin dependent on the defect type, three branches of tr ansverse local oscillations or two branches of longitudinal ones exist . The dispersion law of those does not depend on parameters of conduct ion electrons. The electronic subsystem essentially changes the struct ure of displacement field in semiconductors in comparison with dielect rics. Because of the Coulomb screening of the defect by conduction ele ctrons, the space near the defect Could be divided into the near (r < r(D)) and distant (r >> r(D)) zones with different scales of exponenti al decreasing of displacement amplitudes (r(D) is Debye's radius of th e screening).