Radiative lifetime of boron-bound excitons in diamond

Abstract

We report the ultraviolet absorption of boron-bound excitons at low temperature in a single crystal of diamond grown by chemical vapor deposition. The no-phonon (NP) and phonon-assisted lines are identified by comparison with cathodoluminescence. The oscillator strength of the NP lines was found to be 3.0 × 10−5 based on the measured absorption cross-section. This value is discussed in terms of the scaling law known for doped silicon, where the oscillator strength varies proportionally to E loc 2.5, with Eloc being the localization energy of excitons on acceptors. More importantly, we also could assess the oscillator strength of the dominant transverse optical phonon-assisted transition, which is found to be equal to 1.2 × 10 − 3. The associated radiative lifetime for the boron-bound exciton is 1.8 μs, which is much longer than the non-radiative Auger lifetime that governs its decay.