Embedded Binary Eutectic Alloy Nanostructures as Phase Change Materials

Phase change materials are essential components of both optical data storage and emerging static random access memory technologies. We suggest a new approach to development of phase change memory materials: embedded binary eutectic-alloy nanostructures. The approach exploits the unique properties binary eutectic-alloys that emerge when they are embedded within nanoscale voids. The equilibrium, as-grown, morphology of GeSn nanostructures within SiO$_2$ is a phase separated, bi-crystalline, bi-lobed state. The rapid cooling following pulsed laser melting stabilizes an amorphous, homogeneously mixed state. Subsequent annealing recrystallizes the bi-lobed state. Further, the composition of the alloy can be used to tune the recrystallization temperature over the range of temperatures between 150C and 500C. Thus these nanostructures display the requisite crystalline-amorphous-crystalline transition, and enable tuning of the relevant transformation temperatures.