CONVERGENT-BEAM ELECTRON-DIFFRACTION ANALYSIS OF GASE CRYSTALS GROWN FROM THE MELT BY DIFFERENT DOPING ELEMENTS

A systematic investigation of the structural modifications of GaSe crystals, grown from the melt by different doping elements, has been performed by convergent-beam electron diffraction technique, in order to analyse the dependence of the structure on the doping atoms. Iodine-doped crystals have shown the epsilon - 2H hexagonal and gamma - 3R rhombohedral polytypes. The structure of crystals doped either by silver, or copper, or cadmium, or zinc, or arsenic has been proved a mixture of the epsilon - 2H hexagonal and of gamma, 9 R, 12 R 15 R rhombohedral phases. Ingots doped either by zinc or arsenic have shown the epsilon polytype prevailing in some zones and the gamma structure in the other ones. The epsilon modification is dominant in ingots doped by the remaining atoms.