Coupling the Multi Phase-Field Method with an Electro-Thermal Solver to Simulate Phase Change Mechanisms in Ge-rich GST based PCM

The ternary alloy GeSbTe is widely used as material for phase-change memories. Thanks to an optimized Ge-rich GeSbTe alloy, the crystallizion temperature of the alloy is increased and the stability requirements of high working temperature required for automotive applications are fullfilled, but the crystallization of the Ge-rich alloy proceeds with a composition change and a phase separation. We have developed a multi-phase-field model for the crystallization of the Ge-rich GeSbTe alloy and we have coupled it to an electro-thermal solver. This model is able to capture both the emergence of a two-phase polycristalline structure starting from an initially amorphous material, and the melting and recrystallization during the device operations.