Electron Spin Resonance of Ultrafine Si Particles

A previously reported EX center is a new defect observed in thermal SiO2 layer on Si. The detailed characteristics of this defect have not been clarified yet. The present work reports on the creation, the activation and the passivation of the EX center by thermal treatment in ultrafine Si particles. The electron spin resonance signal of the EX centers was emphasized by annealing in vacuum and reduced by annealing in oxygen. The intensity of the EX signal varied reversibly with the pressure of ambient oxygen.