Enhancing nucleation in phase-change memory cells

An apparatus comprising:

• multiple phase-change memory (PCM) cells;
• and
• at least one signal generator in at least selective communication with one or more of the PCM cells, the at least one signal generator configured to apply a nucleation signal and a programming signal to the PCM cells, the nucleation signal configured to result in nucleation sites within a PCM cell receiving the nucleation signal, the nucleation sites being a pre-structural ordering of molecules of PCM material within the PCM cells, the pre-structural ordering occurring prior to the molecules being placed in a subsequent crystalline-growth phase;
• wherein the nucleation signal includes an initial ramp-up nucleation portion having a rising leading edge leading to a maximum amplitude of the nucleation signal, the rising leading edge lasting longer than 10 nanoseconds;
• and
• wherein the programming signal begins at an amplitude at least as great as the maximum amplitude of the nucleation signal, and extends for a selected period of time to achieve a desired level of crystallinity within a PCM cell receiving the nucleation signal and the programming signal.