Abstract
Vacancy-type defects created by neutron irradiation of floating-zone silicon containing hydrogen with a neutron dose of 1.2 × 1018cm−2 have been studied by positron lifetime spectroscopy and infrared absorption spectroscopy. The positron-trapping rates due to V-type and V2 defects are 11.1 and 5.3 ns−1. The trapping rate of V-type defects decreases markedly from 125 to 200°C, mainly because of annealing out of P-V and V-H complexes; a broad “negative-annealing” peak in the range 200–550°C is observed and attributed to the formation and annealing out of O-V-H and V2-O complexes. The trapping rate of V2-type defects shows a broader “negative-annealing” peak above 200°C due to neutron-induced disordered regions; the annealing behaviour above 400°C agrees very well with that of two strong Si-H stretching vibration infrared bands (divacancy-hydrogen complexes). V4 appears at 125 and 200–250°C; V4, V5 and/or larger vacancy clusters appear in the range 350–600°C with a relative intensity less than 9.6% and a trapping rate less than 0.6 ns−1.