Innovative Nanocomposites for Low Power Phase‐Change Memory: GeTe/C Multilayers

Innovative nanocomposites consisting of [(GeTe)(4 nm/)C-1 nm](10) multilayers (MLs) deposited by magnetron sputtering are integrated in phase-change memory (PCM) test devices with a "wall structure." Scanning transmission electron microscopy (STEM) shows that an ML structure, with crystallized GeTe layers, is kept after integration in as-fabricated devices and also after an additional annealing of the devices at 425 degrees C. The programming current (RESET current) required to reach the high resistance state of [(GeTe)(4 nm)/C-1 nm](10) ML devices decreases by 45% after annealing at 425 degrees C. The reduction in RESET current is 55% and the reduction in drift coefficient is about 40% in ML devices annealed at 425 degrees C compared to similar devices incorporating Ge2Sb2Te5. STEM imaging, coupled with nano-beam electron diffraction and electron energy loss spectroscopy, of ML devices in the high resistance state shows that the RESET current reduction after annealing is correlated to a reduction of the amorphized volume.