OPTICAL STUDIES OF SELF-TRAPPED HOLES AND EXCITONS IN BERYLLIUM-OXIDE

Time-resolved spectra, decay kinetics, degree of polarization of the l uminescence and transient optical absorption induced by irradiation of BeO with an electron, synchrotron and subsequent laser pulses have be en studied. It is found that the two pairs of slowly and fastly decayi ng intrinsic luminescence bands at 6.7, 4.9 and 4.4 eV are associated with the two different types of the self-trapped excitons. The 1.7 eV transient optical absorption band and the ultra-violet absorption band at 3.6 eV are attributed to the electron and hole components of the s elf-trapped excitons, respectively. The transient optical absorption b and with decay time of 6.5 ms is found to be due to the self-trapped h oles. The models of self-trapped excitons and holes are discussed on t he basis of the present experimental results.