The defect properties of single crystals were reviewed with regard to intrinsic and impurity-related cation and anion point defects, optical transitions in defects and their luminescence emissions, color centers, the electronic structure of B2+, Al2+, Zn+ and [Li]0 impurity defects, accumulation and annealing of point defects (table 2), thermally stimulated luminescence, non-isothermal annealing of paramagnetic centers, and thermally stimulated recombination processes. The study of elementary point defects in this oxide, and of the radiative decay of low-energy electronic excitations showed that there were both free excitons of high mobility and favorable conditions for self-trapping. The present oxide exhibited 2 channels for exciton self-trapping. These channels were differentiated by their hole core structure, and their spectral and luminescence characteristics. It followed that a unique situation was possible in this oxide when, during electron and hole recombination, the preferred creation of self-trapped excitons occurred whose radiative annihilation determined the intrinsic luminescence at 4.9eV.

I.N.Ogorodnikov, A.V.Kruzhalov: Materials Science Forum, 1997, 239-241, 51-6

Table 2

Point Defects in BeO Single Crystals

* octahedral interstitial site