|Research Area||Materials Science|
|Principal Investigator(s)||Michele Parrinello|
Phase change materials are widely used in optical information storage (DVD) and are the active part of the most promising non-volatile memories of new concept, the Phase Change Memory (PCM) device which exploits the large change in conductivity between the crystalline metallic phase and the insulating amorphous phase of a chalcogenide film. Although Ge2Sb2Te5 (GST) is presently the material of choice for PCM, doping and changes in composition of GST are under scrutiny to improve PCM performances and scalability. In spite of their great technological importance, the physical insight in chalcogenide materials and their reversible crystal-to-amorphous phase-change mechanisms is still far from being satisfactory. By making use of a novel ab-initio molecular dynamics scheme (Kühne et al., Phys. Rev. Lett. 98, 66401 (2007)), developed in the group of the principal investigator, we have recently provided the first reliable atomistic model of amorphous GST by quenching from the melt. In the present project we plan to extend the ab-initio simulations to other ternary systems along and off the pseudo-binary line (GeTe)x(Sb2Te3)y in order to establish useful relationships among the microscopic structure, the stability of the amorphous phase and the crystallization speed measured experimentally. The simulation results would provide critical insight for the search of new better performing materials in this class for PCM applications.