Temperature Dependent Phase Segregation and morphology evolution in Ca1-xBaxF2 Solid Solution grown on Si(001) with an Epitaxial CaF2 Sublayer

Abstract

The work presents the results of synthesizing epitaxial heterostructures based on the Pb_{1- y}Sn_yTe/BaF₂/Ca_1-xBa_xF₂/CaF₂/Si(001). system. A comprehensive study of these heterostructures was performed, surface morphology characterized, lattice parameters of each sublayer determined, and the temperature dependence of phase segregation of the Ca_1-xBa_xF₂ solid solution into binary components was identified. Optimization of the growth conditions of CaF₂ on Si(001) reduced the surface area occupied by pit defects by 14%. It was shown that the use of a metamorphic Ca_1-xBa_xF₂ buffer layer improves lattice constant matching between CaF₂ and BaF₂ layers. It was established that the optimal growth temperature of the Ca_1-xBa_xF₂ solid solution, providing maximum surface planarity, is around 300°C, with further temperature increase to 475°C and above leading to solid solution segregation.