Luminescence excitation of pure and impure BeO single crystals using synchrotron radiation

Abstract

Absorption, reflection, UV and VUV luminescence excitation and thermoluminescence excitation spectra have been measured for BeO and BeOZn crystals in the energy range from 8 to 35 eV, using synchrotron radiation. The nature of electronic excitations in the fundamental absorption edge region is discussed; the value of the forbidden-gap energy, E g, is estimated as 10.6 eV for BeO. Intrinsic luminescence with a 6.7 eV maximum for BeO and impurity luminescence with a 6.0 eV maximum for BeOZn are due to the relaxation of both optically created self-trapped or impurity-trapped excitons. The multiplication effect of electronic excitations with E>2 E g (or E≥2 E ex for 6.7 eV luminescence) for beryllium oxide is due to the inelastic scattering of hot photoelectrons or hot photoholes.