In‐Memory Computing of Multilevel Ferroelectric Domain Wall Diodes at LiNbO₃ Interfaces

Abstract

Direct data processing in nonvolatile memories can enable area‐ and energy‐efficient computation, unlike independent performance between separate processing and memory units; repetitive data transfer between these units represents a fundamental performance limitation in modern computers. Spatially mobile conducting domain walls in ferroelectrics can be redirected between drain, gate, and source electrodes to function as nonvolatile transistors with superior energy efficiency, ultrafast operating and communication speeds, and high logic/storage densities. Here, in‐memory computing is demonstrated using multilevel domain wall diodes at LiNbO3 interfaces. Ultrathin domains within interfacial layers between each mesa‐like memory cell and the contact electrodes can rectify diode‐like domain wall currents with on/off current ratios exceeding 107 at low operating voltages, surpassing the performance of traditional p‐n junctions using built‐in potentials across depletion layers. NOT, NAND, and NOR gate logic functions are demonstrated, providing insights into high‐density integration of multilevel storage and computational units in all‐ferroelectric domain wall devices.

Tuning Local Conductance to Enable Demonstrator Ferroelectric Domain Wall Diodes and Logic Gates

“…Simple Boolean logic gates, the operation of which is entirely dependent on the local manipulation of domain wall conductivity, have hence been established, further pushing forward possibilities for domain wall-based nanoelectronics. [23] The insights developed are complementary to those seen by Sun et al [24] where NOT, NOR, and NAND logic gates were realized by moving conduct-ing domain walls in and out of contact with patterned surface thin film electrodes. [24] Importantly, however, the mechanisms of operation involved in the two studies are fundamentally different.…”

“…This diode mechanism of making and breaking contact between domain walls and electrodes differs from that seen in our study, as the conductivities of the domain walls themselves were not explicitly manipulated; nevertheless, the half‐wave rectification and creation of NOT, NOR, NAND, and OR logic gates in very recently published work (performed in parallel with the research we report herein) is highly noteworthy. [ 24,31 ]…”

“…This diode mechanism of making and breaking contact between domain walls and electrodes differs from that seen in our study, as the conductivities of the domain walls themselves were not explicitly manipulated; nevertheless, the half-wave rectification and creation of NOT, NOR, NAND, and OR logic gates in very recently published work (performed in parallel with the research we report herein) is highly noteworthy. [24,31] 3: a) "AND" gates in the first layer followed by an "OR" gate and b) "OR" gates in the first layer followed by an "AND" gate. c) All possible logic input combinations are applied through time, and d,e) the output voltage is simultaneously recorded.…”

“…[ 24 ] where NOT, NOR, and NAND logic gates were realized by moving conducting domain walls in and out of contact with patterned surface thin film electrodes. [ 24 ] Importantly, however, the mechanisms of operation involved in the two studies are fundamentally different.…”

High-Power LiNbO3 Domain-Wall Nanodevices

“…The high-power diodes can function as selectors in phase-change memory and half-wave/full-wave rectifiers in more integrated power electronic systems, , besides various logic gates in-memory computating. , Figure a shows the half-wave rectification of an LNO DW diode ( w × l × h = 35 × 150 × 80 nm 3 ) when θ = 15° under input sine waves in amplitudes of 2 – 7 V in a repetitive frequency of 10 Hz. The on-current appears when V > V on .…”