arXiv subjects

Spencer Ware

Publications and source records attributed to Spencer Ware.

2 recordsLinked to original sources

arXiv2025

Kilobyte-Scale, Selector-Free, Temperature-Hard AlScN Ferroelectric Diode Crossbar Arrays

We report the fabrication and characterization of kilobyte-scale, selector-free, ferroelectric (FE) diode crossbar memory arrays based on aluminum scandium nitride (AlScN). Utilizing a fully CMOS back-end-of-line (BEOL) compatible process, we fabricated 2-kilobyte (128 $\times$ 128) arrays with device diameters down to 5 $\mu$m, achieving memory densities up to 2500 bits/mm$^2$. Large-scale electrical characterization across 1000 randomly selected devices reveals a yield rate of 95.2%, a tight switching voltage distribution with a coefficient of variation (CV) of 0.003, and consistent on/off ratios of around 10 with a CV of 0.27. We demonstrate selector-free read and program operations of the array, enabled by the high nonlinearity, rectification, and uniform switching behavior of the FE diodes. Furthermore, we verified consistent ferroelectric switching during array operation at temperatures up to 600 $^\circ$C. Our results highlight the potential of AlScN FE diode arrays for energy-efficient, high-density memory applications and lay the groundwork for future integration in compute-near-memory, high-temperature memory, and analog compute-in-memory systems.

cond-mat.mes-hall↗

arXiv2024

Al0.68Sc0.32N/SiC based metal-ferroelectric-semiconductor capacitors operating up to 1000 {\deg}C

Ferroelectric (Fe) materials-based devices show great promise for non-volatile memory applications, yet few demonstrate reliable operation at elevated temperatures. In this work, we demonstrate Ni/Al0.68Sc0.32N/4H-SiC metal-ferroelectric-semiconductor capacitors for high-temperature non-volatile memory applications. Our 30-nm thick ferroelectric Al0.68Sc0.32N film grown on SiC exhibits stable and robust ferroelectric switching up to 1000{\deg}C. The coercive field decreases linearly from -6.4/+11.9 MV cm-1 at room temperature to -3.1/+7.8 MV cm-1 at 800{\deg}C, further reducing to -2.5 MV cm-1 at 1000{\deg}C. At 600{\deg}C, the devices achieve remarkable reliability with ~2000 endurance cycles and over at least 100 hours of retention with negligible polarization loss. At 800{\deg}C, the devices retain data for at least 10,000 seconds and exceed 400 write cycles. Our results further highlight the potential for ferroelectric AlScN thin-films particularly when paired with SiC semiconductor substrates for high-temperature non-volatile memory.

cond-mat.mtrl-sci↗