Defect-defect hole transfer and the identity of border traps inSiO2films

We have found evidence for hole-transfer events between oxygen-vacancy-related defects in thermal ${\mathrm{SiO}}_2$ films selectively injected with holes using electron paramagnetic resonance (EPR) and capacitance-voltage measurements. We find that hole injection into ${\mathrm{SiO}}_2$ films reveals two types of EPR centers: oxygen-vacancy-related ${\mathit{E}}_{\mathrm{\delta }}^{\mathcal{’}}$ and ${\mathit{E}}_{\gamma }^{\mathcal{’}}$ centers; both centers are positively charged. Upon annealing the Si/${\mathrm{SiO}}_2$ structures at room temperature, the ${\mathit{E}}_{\mathrm{\delta }}^{\mathcal{’}}$ defect transfers its hole to a neutral oxygen-vacancy (${\mathrm{O}}_3$≡Si—Si≡${\mathrm{O}}_3$) site forming the classic ${\mathit{E}}_{\gamma }^{\mathcal{’}}$ center. Electrically, we observe a concomitant growth in the border-trap density, suggesting that some of the transfer-created ${\mathit{E}}_{\gamma }^{\mathcal{’}}$ centers may be the microscopic entities responsible for the border traps. These results constitute spectroscopic evidence that hole transfer between defect sites can occur over extremely long time scales (hours) in ${\mathrm{SiO}}_2$ films.