Gate-tunable memristive phenomena mediated by grain boundaries in single-layer MoS2

Abstract

Continued progress in high-speed computing depends on breakthroughs in both materials synthesis and device architectures. The performance of logic and memory can be enhanced significantly by introducing a memristor, a two-terminal device with internal resistance that depends on the history of the external bias voltage. State-of-the-art memristors, based on metal-insulator-metal (MIM) structures with insulating oxides, such as TiO₂, are limited by a lack of control over the filament formation and external control of the switching voltage. Here, we report a class of memristors based on grain boundaries (GBs) in single-layer MoS₂ devices. Specifically, the resistance of GBs emerging from contacts can be easily and repeatedly modulated, with switching ratios up to ∼10(3) and a dynamic negative differential resistance (NDR). Furthermore, the atomically thin nature of MoS₂ enables tuning of the set voltage by a third gate terminal in a field-effect geometry, which provides new functionality that is not observed in other known memristive devices.

Engineering the Electronic Properties of Two‐Dimensional Transition Metal Dichalcogenides by Introducing Mirror Twin Boundaries

“…As an interesting application involving GBs, a memristor was fabricated using MoS 2 , where the memristive behavior was ascribed to GB migration. [21] Concerning their characterization, grain boundaries are often visible as lines in photoluminescence or Raman images. [14] Alternatively, oxidation can be used to make the grain boundaries easier to distinguish under atomic force microscopy, scanning electron microscopy, or optical microscopy.…”

Gate‐Tunable Resonant Raman Spectroscopy of Bilayer MoS2

“…Moreover, realization of possible new applications also benefits from the development of gate control, such as in the observation of gate-tunable memristive device. [7] Raman spectroscopy is a versatile probe in studying the crystalline and vibrational properties of TMDs. [8][9][10][11][12] Gatetunable phonon properties in graphene, [13,14] MoS 2 , [15] and black phosphorus [16] have also been reported.…”

Advanced Scanning Probe Microscopy of Graphene and Other 2D Materials

“…The abrupt change of the cantilever phase (fraction of phase shift >0.9, see Figure 3f) in the EFM images across a bisecting grain boundary (GB) in MoS 2 memory devices indicated that the electrostatic potential drops primarily at the grain boundary, i.e., the GB is resistive, consistently with the overall higher resistance of a bisecting-GB memristor compared to a bridge-GB memristor. Because the local surface potential and thus resistivity varies as a square root of the variation in the EFM phase signal, it was evaluated that more than 94% of the total device resistance would come from the grain boundary [18].…”

“…Various memory devices have been fabricated with 2D materials, showing low power and energy consumption [16] as well as the possibility to be integrated in flexible devices [17]. Memristors based on grain boundaries in single layer MoS 2 devices have shown switching ratios up to~10 3 [18].…”