NEW VISIBLE LUMINESCENCE SPECTRA FROM SYNTHETIC TYPE IIA DIAMOND

Two luminescence bands with new features different from the 'band A' e mission are found at 2.10 and 2.44 eV in a high-pressure synthetic dia mond by interband photoexcitations in the indirect-edge absorption reg ion. The temperature dependence, injection power dependence, growth an d decay of these bands and thermoluminescence are studied. On the basi s of these results, the 2.10 eV band is assigned to the donor-acceptor -like recombination of close pairs and the 2.44 eV band is due to the recombination of free holes and trapped electrons at deep donors. The thermal activation energy of the acceptor-like state responsible for t he 2.44 eV band is estimated to the 0.25 eV from the analysis of the t hermoluminescence glow curve.