Variations in thermoelectric power and D.C. resistivity in sequentially irradiated and annealed n- and p-type doped α-tin

Sequential irradiations and anneals were carried out on n- and p-type α-tin filaments. Irradiations were performed at 4.5K for a nominal electron beam energy of 0.90MeV. A carrier removal rate varying with defect concentration was found. Isochronal anneals were carried out over the temperature range 20 to 47K. Four first-order stages with activation energy scaling factors of 67, 90, 106 and 122MeV were resolved in order of increasing temperature. A fractional defect recovery scheme was deduced with defect concentration ratios given by Isub(A): Isub(B): Isub(C): Isub(D)=84:4:6:6 for the four stages. An average constant carrier removal rate was used to deduce charge carrier mobilities from both damage and annealing data. It was found that the electron mobilities were inconsistent with those deduced from the theory of ionized impurity scattering. A model is proposed requiring that the majority of the defects result in deep acceptor sites. In addition, shallow defect states positioned somewhat above the GAMMA8+ conduction and valence band junction are proposed to account qualitatively for the observed results. (author)