SHALLOW DONOR IN BURIED OXIDE SI-ON-INSULATOR STRUCTURES REVEALED BY GAMMA-IRRADIATION-INDUCED ELECTRON-SPIN-RESONANCE ACTIVATION

Si-on-insulator structures formed by implantation of oxygen (SIMOX) in a single step to a dose almost-equal-to 1.8 x 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. Gamma-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 parallel-to [0 0 1]) = 1.999 89 +/- 0.000 04 and g perpendicular-to = 1.999 71 +/- 0.000 04 and spin density (S = 1/2) almost-equal-to 1.1 x 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 SiO2 by gamma-irradiation. Possibly, this centre relates to the new donors recently suggested from transport measurements.