Volume 51 (2007)

MORPHOLOGY OF ETCH PITS AND DISLOCATION DENSITY ON (111) SURFACE OF RARE - EARTH DOPED CaF₂ CRYSTALS
Pages 40-43
Andreea Pruna, G. Buse, E. Preda and Irina Nicoara

Abstract
Pure, YbF₃- and ErF₃ - doped calcium fluoride crystals have been grown using the vertical Bridgman method. In order to study the etch pits morphology and the dislocation density the chemical etching method have been used. This method consists in immersing the cleaved sample, the (111) plane, in 4N HCl at 60⁰C for 5 minutes. The obtained etch pits have triangular or hexagonal shapes, depending on the dopant type, YbF₃ or ErF₃. The dislocation density depends also on the dopant type and concentration.