Paramagnetic resonance of E′-type centers in Si-implanted amorphous SiO 2. Si 29 hyperfine structure and characteristics of Zeeman resonances

Abstract

Electron paramagnetic resonance spectra were measured on SiO 2 glasses implanted with Si ions to a fluence of 6 × 10 16 cm −2 at an acceleration voltage of 160 kV. Three sets of doublets with different separation were observed in Si 29-implanted substrates and were ascribed to primary hyperfine structures due to a Si 29 nucleus ( nuclear spin = 1 2 ). The doublets with separation of 44.0 and 9.0 mT were attributed to ·Si 29 ≡ O 3 (E′-center, where the dot and three parallel lines denote the unpaired electron and three separate bonds, respectively) and ·Si 29 ≡ Si 3 (similar to D center in amorphous Si or P b center in Si/SiO 2 interface) radicals, respectively, and the doublet with a separation of ∼ 23 mT is tentatively assigned to a ·Si 29 ≡ Si n O 3 − n ( n = 1 or 2). The area intensity ratio of these three doublets was approximately 2.5 (44.0 mT): 2.5 (23.0 mT): 1.0 (9.0 mT). Zeeman resonances of E′ centers have a broader spread in g 2 and are less saturable to microwave power than those of normal E′ resonances. It is suggested that these are common characteristics of E′ resonances in compacted amorphous SiO 2.