Phase field simulation of low-temperature, pressure-induced amorphization in Ge2Sb2Te5

Abstract

The phase change materials (PCMs) have garnered significant attention due to their unique physical properties for future electronic and optoelectronic devices. While the focus has primarily been on phase transition due to temperature stimuli, pressure-induced phase transitions have been largely ignored. Here, we developed a phase-field model to investigate high-pressure amorphization of crystalline Germanium-antimony-tellurium (c-GST) as the model material. While the pressure independent bulk modulus leads to temperature independent amorphization pressure, significantly below the experimental/atomistic results, the proposed model based on Murnaghan's equation of state (EOS), which includes elastic, transformational and thermal strains, can replicate the temperature dependency of the amorphization pressure. Additionally, the difference between onset and completion amorphization pressure for defective c-GST was successfully captured, in agreement with experimental/atomistic results. Simulations on defective GST show the importance of void/vacancy clusters in lowering the amorphization pressure and accelerating the phase transition.