ELECTRON-NUCLEAR DOUBLE-RESONANCE INVESTIGATION OF IRON-ACCEPTOR PAIRS IN SILICON

With stationary electron nuclear double resonance (ENDOR) the two Fe-i -Al-s pairs having trigonal and orthorhombic symmetry, respectively, a nd the trigonal Fe-i-B-s pair have been investigated. The hyperfine an d quadrupole interactions with the interstitial Fe-57 and the acceptor nuclei Al-27 and B-11, respectively, have been determined with higher precision than possible with previous electron paramagnetic resonance (EPR) investigations. Also the interactions with several shells of Si -29 neighbour nuclei around the pairs have been determined. For all th ree pair defects 'negative' stationary ENDOR signals from Al-27 and B- 11 have been observed, where the saturation of the partially saturated EPR signal is enhanced upon induction of a nuclear magnetic transitio n in contrast to the usual positive stationary ENDOR signals where it is diminished.