Optical study of some interstitial-related centres in CVD diamond

Luminescence and optical transmittance measurements were performed on irrad iated natural diamond crystals and on synthetic films. Their results show t hat variations in luminescence with annealing can be due to changes in the non-radiative processes rather than in che concentration of the investigate d centre. In particular, emission from the interstitial-related 3H centre i ncreases when the neutral vacancy (GR1) anneals out, showing that the GR1 c an effectively quench 3H emission. The 3H centre was found to be stable up to 900 degrees C in irradiated CVD and natural diamond. As-grown CVD films also show the presence of this centre as well as of a defect, which is assi gned to the distorted TR12 centre. The latter defect, labeled as TR12', sho ws remarkable temperature stability, being present in films grown at 2100 d egrees C.