Lattice relaxation in silicon doped with 4d and 5d transition metals

Abstract

Photoionization cross-section spectra from deep centers in silicon doped with technologically important 4d and 5d transition elements were analyzed by the Ridley and Amato lattice coupling model to determine threshold energy and lattice relaxation parameters corresponding to optically induced transitions involving either band. The average optic phonon energy is 50 meV. Electron transitions to the conduction band from the silver, platinum, and gold acceptor centers have, respectively, threshold energies (in meV) ET0 =550,226, and 570. For silver and gold, the Huang–Rhys parameter S could not be determined because of a mixture of both allowed and forbidden transitions; for platinum, S=0.3. Hole transitions from the valence band to the same centers have, respectively, ET0 =580, 905, 590, and S=1.3, 0.5, 0.8. Hole transitions from the valence band to the donor centers of these elements are, respectively, ET0 =340, 320, 335 and S=1.2, 1.4, 0.4. ET0, and S values are uncertain to within ±5 meV and ±0.05, respectively. Electron transition data from the donor centers of these elements to the conduction band are not available or insufficient to allow analysis of the threshold region.