Towards ultimate scaling limits of phase-change memory

Data storage based on a reversible material phase transition (e.g. amorphous to crystalline) has been studied for nearly five decades. Yet, it was only during the past five years that some phase-change memory technologies (e.g. GeSbTe) have been approaching the physical scaling limits of the smallest possible memory cell. Here we review recent results from our group and others, which have achieved sub-10 nm scale PCM with switching energy approaching single femtojoules per bit. Fundamental limits could be as low as single attojoules per cubic nanometer of the memory material, although approaching such limits in practice appears strongly limited by electrical and thermal parasitics, i.e. contacts and interfaces.