A thermodynamically-consistent multi-physics framework for crystallization of phase-change material

Abstract

Phase Change Materials (PCMs) have a diverse set of technological applications, including phase-change random access memory devices (PCRAMs), and their behavior can be understood based on a complex set of coupled physical phenomena, e.g., heat transfer, phase transition, and thermoelectric effects. A detailed understanding of these phenomena and their interactions during the operation of a cell results in an efficient and compact design of the devices. This paper reports our development of a coupled, thermodynamically-consistent model to study the interplay among various parameters in PCRAMs, e.g., temperature, electrical current, thermoelectric effect, and crystal nucleation/growth. A Phase-Field (PF) model was developed to model the phase transition (PT). Also, we show that incorporating the heat of crystallization in heat transfer model results in identifying a self-heating mechanism in PCRAMs and consequently self-sustaining crystallization; crystallization continues even after the external voltage is turned off.