PHOSPHORESCENCE IN HIGH-PRESSURE SYNTHETIC DIAMOND

Long-lived phosphorescence has been investigated in high-pressure synt hetic boron-doped diamond. The spectrum exhibits two broad bands at pe ak energies of 2.1 and 2.5 eV after ultra-violet light excitation. The typical lifetime for both the bands shows a monotonous decrease from 50 s to 300 ms as the temperature rises from 200 to 400 K. The integra ted intensities of the 2.1 and 2.5 eV bands increase as the temperatur e rises to 350 and 360 K, respectively. Beyond these temperatures, the intensities decrease rapidly as temperature rises. A model based on a recombination process involving both a shallow acceptor and a deep do nor has been examined by theoretical fitting with the temperature depe ndence of the lifetime and the integrated intensity. It is concluded f rom the analysis that a shallow acceptor with an activation energy of 0.35 eV, which can be assigned as that of boron, plays a key role in t he phosphorescence.