Aluminum scandium nitride-based metal–ferroelectric–metal diode memory devices with high on/off ratios

Abstract

In this Letter, we report a back-end-of-line (BEOL), complementary metal–oxide–semiconductor (CMOS)-compatible Al0.64Sc0.36N-based ferroelectric diode that shows polarization-dependent hysteresis in its leakage currents. Our device comprises a metal/insulator/ferroelectric/metal structure (Pt/native oxide/Al0.64Sc0.36N/Pt) that is compatible with BEOL temperatures (≤ 350 °C) grown on top of a 4-in. silicon wafer. The device shows self-selective behavior as a diode with > 105 rectification ratio (for 5 V). It can suppress sneak currents without the need for additional access transistors or selectors. Furthermore, given the polarization-dependent leakage, the diode current–voltage sweeps are analogous to that of a memristor with an on/off ratio of ∼ 50 000 between low and high resistance states. Our devices also exhibit stable programed resistance states during DC cycling and a retention time longer than 1000 s at 300 K. These results demonstrate that this system has significant potential as a future high-performance post-CMOS compatible nonvolatile memory technology.

Reconfigurable Compute-In-Memory on Field-Programmable Ferroelectric Diodes

“…The PUND result indicates a remanent polarization ~150 µC/cm 2 , as shown in Fig. 2c, and in agreement with prior observations [15][16][17][18][19]. To further verify the ferroelectric switching, a dynamic current response was carried out, in which peaks corresponding to ferroelectric switching were observed (Supplementary Fig.…”

“…It has also been shown to be one of the most promising candidates for high-performance ferroelectric memory devices, scalable down to < 10 nm in thickness [18]. The AlScN films were characterized electrically and exhibit large coercive fields, E C , of 2-4.5 MV/cm [15][16][17][18][19]. This is important for scaling to thinner ferroelectric layers, all while maintaining a large memory window, high ON/OFF ratio and good retention [16,19].…”

“…The AlScN films were characterized electrically and exhibit large coercive fields, E C , of 2-4.5 MV/cm [15][16][17][18][19]. This is important for scaling to thinner ferroelectric layers, all while maintaining a large memory window, high ON/OFF ratio and good retention [16,19]. When combined with high measured remnant polarizations -P r of 80-150 μC/cm 2 [15][16][17][18][19] -this leads to a significant tunneling electro-resistance effect, based on strong tunnel barrier modulation, thus giving a high ON/OFF ratio (Supplementary Note 1).…”

“…This is important for scaling to thinner ferroelectric layers, all while maintaining a large memory window, high ON/OFF ratio and good retention [16,19]. When combined with high measured remnant polarizations -P r of 80-150 μC/cm 2 [15][16][17][18][19] -this leads to a significant tunneling electro-resistance effect, based on strong tunnel barrier modulation, thus giving a high ON/OFF ratio (Supplementary Note 1). The field programmability, non-volatility and non-linearity of these devices can be leveraged for multiple, primitive data operations such as storage, search, and neural networks without the need for additional tansistors, as shown in b-d. b.…”

Ferroelectricity in untwisted heterobilayers of transition metal dichalcogenides

“…The device characteristics are also similar to ferrodiode behavior as reported by Liu et al . ( 27 ). Thus, although we use the term FTJ to describe our device, distinguishing between the two requires additional observations.…”