A comparison of low energy Auger spectra of the nitrides and oxides of the light elements lithium, beryllium and boron

Abstract

Auger spectra obtained from nitrides and oxides of the light elements lithium, beryllium and boron are presented. A comparison of the new data for Li 3N and Be 3N 2 with those observed for BN and the oxides of these elements reveal certain similarities. In contrast to the pure elements having only one decay channel the low energy Auger transition of the electropositive partner in these binary compounds is generally split into a multiplet of several lines. The Auger features of the three elements are quite similar in their oxide spectra as well as in their nitride spectra. However, the energy separation of the lines in the multiplets of Li, Be and B varies with different electronegative partners in the compound. The effect is controlled by the l 1 levels of nitrogen and oxygen, which open with their local density of states extra decay channels at the site of the excited atom. Some features in the spectra, however, require further consideration. The high energy peak of BN may be the direct nonradiative recombination of a core exciton. For the interpretation of the low energy line of each multiplet two alternative models can be applied. According to the first one it may be due to a double Auger transition involving an unoccupied, localized level in the final state. The other model assumes partial localization in the bonding which results in different final states due to distinct effective interaction energies of the two holes.