POINT-DEFECTS IN CUBIC BORON-NITRIDE AFTER NEUTRON-IRRADIATION

The production of point defects induced by reactor neutrons and the thermal behavior of defects in sintered cubic boron nitride are investigated using the optical absorption and electron spin resonance (ESR) methods. A strong structureless absorption over the visible region was observed after fast neutron irradiation to a dose of 5.3 X 10(16) n/cm2 (E>0.1 MeV) at 25 K. This specimen also shows an ESR signal with g-value 2.006+/-0.001, which can be tentatively identified as an electron trapped in a nitrogen vacancy. On examination of the thermal decay of the signal, the activation energy for recovery of the defects was determined to be about 1.79 eV.