Positron probing of open vacancy volume of phosphorus-vacancy complexes in float-zone n-type silicon irradiated by 0.9-MeV electrons and by 15-MeV protons

For the first time the samples, cut from the same wafer of crystals of float-zone silicon, n-FZ-Si(P) and n-FZ-Si(Bi), were subjected to irradiation with 0.9-MeV electrons and 15-MeV protons at RT for studying them by low-temperature positron annihilation lifetime spectroscopy. Measurements of Hall effect have been used for the materials characterization. The discussion is focused on the open vacancy volume (V-op) of the thermally stable group-V-impurity-vacancy complexes comprising the phosphorus atoms; the bismuth-related vacancy complexes are briefly considered. The data of positron probing of PV pairs (E-centers), divacancies, and the thermally stable defects in the irradiated n-FZ-Si(P) materials are compared. Beyond a reliable detecting of the defect-related positron annihilation lifetime in the course of isochronal annealing at similar to 500 C, the recovery of concentration of phosphorus-related shallow donor states continues up to similar to 650-700 C. The open vacancy volumes V-op to be characterized by long positron lifetimes Delta tau(2) similar to 271-289 ps in (gr.-V-atom)-V-op complexes are compared with theoretical data available for the vacancies, tau(V-1), and divacancies, tau(V-2). The extended semi-vacancies, 2V(s-ext), and relaxed vacancies, 2V(inw), are proposed as the open volume V-op in (gr.-V-atom)-V-op complexes. It is argued that at high annealing temperature the defect P-s-V-op-P-s is decomposed. (C) 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim