LUMINESCENCE DECAY TIME STUDIES AND TIME-RESOLVED CATHODOLUMINESCENCESPECTROSCOPY OF CVD DIAMOND

Luminescence decay times of the characteristic electron-beam excited e mission systems in CVD diamond were measured for samples grown by the combustion flame and microwave techniques. For the sharp emission line s between 2.3 and 3.0 eV the decay times range from 9.6 ns for the 2.3 3 eV line to 1.8 mus for the 2.537 eV line. The luminescence intensity of the 1.681 eV silicon-related system initially decreases relatively slowly, followed, after about 3 ns, by a rapid decrease with decay ti me of 2.4 +/- 0.3 ns. This behaviour is attributed to the presence of energy reservoirs coupled to the 1.681 eV excited state. The decay tim e of the blue band A is relatively short and this allows the bandshape s of vibronic systems superimposed on this band to be studied in more detail using time-resolved spectroscopy. In particular, the system wit h a zero-phonon fine at 2.99 eV is shown to have a different vibronic bandshape to the N3 system (with a zero-phonon line at 2.985 eV) with which it was originally confused. In favourable circumstances the samp le-limited spectral resolution in continuously excited measurements is enhanced in the time-resolved spectra.