Monte Carlo simulation of charge transport in amorphous GST

A microscopic particle description of the charge transport process in amorphous GST is presented in this paper, based on the assumption that electrical conduction in the amorphous phase is controlled by defects and trapped carriers. The physical model has been implemented in a Monte Carlo simulation coupled to the Poisson equation for a simple device formed by a nanometric layer of amorphous GST in contact with two planar metallic electrodes. The purpose of our research is to understand how and to which extent different aspects of the microscopic picture influence the electrical properties of the device when external tunable parameters, like operating current and temperature, are varied. Moreover the role of other parameters, often almost unknown in real devices like, e.g., trap energy levels and concentration, trap spatial distribution, is analyzed through focused simulated experiments with the purpose of pursuing a theoretical control of the threshold behavior so important for technological exploitation. Results obtained so far are compared with experiments, analytical models available in the literature, and the outcome of deterministic equations formulated by the authors for the system under investigation.