Novel nanocomposite-superlattices for low energy and high stability nanoscale phase-change memory

Abstract

Data-centric applications are pushing the limits of energy-efficiency in today’s computing systems, including those based on phase-change memory (PCM). This technology must achieve low-power and stable operation at nanoscale dimensions to succeed in high-density memory arrays. Here we use a novel combination of phase-change material superlattices and nanocomposites (based on Ge4Sb6Te7), to achieve record-low power density ≈ 5 MW/cm2 and ≈ 0.7 V switching voltage (compatible with modern logic processors) in PCM devices with the smallest dimensions to date (≈ 40 nm) for a superlattice technology on a CMOS-compatible substrate. These devices also simultaneously exhibit low resistance drift with 8 resistance states, good endurance (≈ 2 × 108 cycles), and fast switching (≈ 40 ns). The efficient switching is enabled by strong heat confinement within the superlattice materials and the nanoscale device dimensions. The microstructural properties of the Ge4Sb6Te7 nanocomposite and its high crystallization temperature ensure the fast-switching speed and stability in our superlattice PCM devices. These results re-establish PCM technology as one of the frontrunners for energy-efficient data storage and computing.

A Fast and High Endurance Phase Change Memory Based on In-Doped Sb2Te3

“…Recently, in accordance with crystallization theory, the most popular strategy to accelerate the crystallization process is to introduce crystalline precursors as the stable structural fluctuations into the amorphous phase of phase change materials, − which can increase the number of nuclei, shorten the incubation period, reduce the crystallization energy threshold and reduce the interface energy for crystallization, thus significantly increase the crystallization rate of PCM. Through the above material engineering, the Ti doping system, Y doping system, heterostructure system, nanocomposite system and superlattices system have been reported to show fast switching speeds. Even more, the subnanosecond operation speed, , as fast as DRAM, has been successfully achieved in PCM devices.…”