Phase-change RAM modelling and design via a Gillespie-type cellular automata approach

A Gillespie type cellular automata (GCA) simulator capable of spatio-temporal modelling of the amorphization and crystallization behaviour in phase change devices, such as random access memory cells (PCRAM), during complex annealing cycles is presented. The model is based on the bulk, electrostatic and surfaces energies to produce rates of nucleation, growth and dissociation of crystallites made of “monomers”. To deal with the events during the phase change transformation a stochastic Gillespie type algorithm is used. The phase change dynamics are coupled with the electrical and thermal fluxes to study the switching dynamics associated with the reset and set operations. The potential role of electric field induced nucleation is also investigated briefly.