OPTICAL-ABSORPTION AND EMISSION NEAR THE BAND EDGE OF SRO

A luminescence band at 5.0 eV, with a half-width of 0.33 eV, can be excited at low temperatures in freshly cleaved single-crystal SrO. This is the only band excited over the spectral range from 2 to 5.5 eV by either incident electrons or ultraviolet photons. The lifetime of the emission is less than 50 ns at 77 K. The excitation spectrum of the emission has a low-energy peak at 5.4 eV, where the absorption coefficient and the photoresponse of the sample are rising rapidly with increasing photon energy. Another peak occurs in the excitation spectrum at 5.7 eV, which is close to the energy of the first exciton doublet. The experimental results are tentatively interpreted in terms of electron-hole recombination, probably close to an impurity (defect) center. An activation energy of 0.064 ± 0.006 eV is found for thermal quenching of the luminescence. © 1979 The American Physical Society.