Röntgenographische und optische Untersuchungen aufgedampfter Schichten aus Erdalkalichalkogeniden

Abstract

Thin films of chalcogenides of the alkaline earth metals evaporated by electron bombardment are condensed on to a substrate at low temperature (quenching condensation). Debye-Scherrer-diagrams are taken immediately after condensation and during annealing. Moreover, the fundamental optical absorption is measured in the range between 3 and 6 eV.

After condensation at 20° K the films have a high degree of disorder which decreases very slowly with increasing temperature. MgS, MgSe, and MgTe are forced even in an amorphous state. After annealing MgS and MgSe crystallize in a new modification, which can be described by a hexagonal lattice withc/a=1,6. It changes very slowly into the stable NaCl-lattice. The new structure can be explained by the ratio of the ionic radii, the appearence of the amorphous phase by the great polarization of the ions.