Shallow donor in buried oxide Si-On-insulator structures revealed by γ-irradiation-induced electron spin resonance activation

Abstract

Si-on-insulator structures formed by implantation of oxygen (SIMOX) in a single step to a dose ≃ 1.8 × 10 18 O + cm −2 into p-type (0 0 1) Si and high temperature annealing have been studied by K-band electron spin resonance (ESR) at 4.3–31 K. γ-irradiation to a dose of 1 Mrad (Si) is found to introduce a new anisotropic ESR signal originating from a shallow donor in Si. At 4.3 K it is characterized by g (magnetic induction B | [0 0 1]) = 1.999 89 ± 0.000 04 and g ⊥ = 1.999 71 ± 0.000 04 and spin density (S = 1 2 ≃ 1.1 × 10 12 cm −2 . It is tentatively assigned to an oxygen-related double donor intrinsic to SIMOX, which ionization state is tuned by changes in Si band bending resulting from modification of the net charge in adjacent SiO 2 by γ-irradiation. Possibly, this centre relates to the new donors recently suggested from transport measurements.