Crystallization kinetics and phase transformations of zinc- and cadmium diphosphide films

The kinetics of isothermal crystallization of amorphous ZnP₂ films in the temperature range from 730 to 810 K and amorphous CdP₂ films between 630–770 K has been investigated. The kinetic curves of isothermal transformation of amorphous films into crystalline ones have been obtained. For ZnP₂ the transformation occurs as follows: amorphous films → α-ZnP₂ (tetragonal modification) → β-ZnP₂ (monoclinic modification). For CdP₂ – amorphous films → γ-CdP₂ (cubic modification) → β-CdP₂ (tetragonal modification). From the experimentally determined kinetic curves the stability diagrams for ZnP₂ and CdP₂ films have been plotted. The most stable modification in the investigated temperature range are β-ZnP₂ and β-CdP₂ other ones are metastable. The values of effective energy of activation of transformation have been determined.