Robust memristors based on layered two-dimensional materials (1801.00530v1)

Abstract: Van der Waals heterostructure based on layered two-dimensional (2D) materials offers unprecedented opportunities to create materials with atomic precision by design. By combining superior properties of each component, such heterostructure also provides possible solutions to address various challenges of the electronic devices, especially those with vertical multilayered structures. Here, we report the realization of robust memristors for the first time based on van der Waals heterostructure of fully layered 2D materials (graphene/MoS2-xOx/graphene) and demonstrate a good thermal stability lacking in traditional memristors. Such devices have shown excellent switching performance with endurance up to 107 and a record-high operating temperature up to 340oC. By combining in situ high-resolution TEM and STEM studies, we have shown that the MoS2-xOx switching layer, together with the graphene electrodes and their atomically sharp interfaces, are responsible for the observed thermal stability at elevated temperatures. A well-defined conduction channel and a switching mechanism based on the migration of oxygen ions were also revealed. In addition, the fully layered 2D materials offer a good mechanical flexibility for flexible electronic applications, manifested by our experimental demonstration of a good endurance against over 1000 bending cycles. Our results showcase a general and encouraging pathway toward engineering desired device properties by using 2D van der Waals heterostructures.

• The paper demonstrates a breakthrough in memristor technology by using atomically precise vdW heterostructures to achieve >10^6 switching cycles.
• It employs graphene and oxidized MoS₂ to overcome the thermal and mechanical challenges faced by traditional oxide memristors.
• The findings suggest strong potential for harsh environment applications, including aerospace and automotive electronics.

Robust Memristors Using Layered 2D Materials

The paper discusses the development of robust memristors utilizing van der Waals (vdW) heterostructures composed of fully layered two-dimensional (2D) materials, specifically graphene and oxidized molybdenum disulfide (MoS$_{2-x}$O$_x$). The primary goal of the research is to address the thermal stability challenges prevalent in traditional memristors made from oxide materials. Traditional memristors often succumb to device failure when exposed to high temperatures or during mechanical manipulation, making them unsuitable for harsh environment electronics.

Key Innovations and Findings

The paper presents a significant advancement in the materials science domain by fabricating memristors with novel vdW heterostructures that feature atomically sharp interfaces between the graphene electrodes and the MoS$_{2-x}$O$_x$ switching layer. This atomic precision in device fabrication is unattainable in conventional metal/oxide/metal memristor structures. The devices exhibit repeatable bipolar resistive switching with an endurance of more than $10^6$ cycles, a record-high operational temperature of up to 340 °C, and strong mechanical flexibility withstanding over 1000 bending cycles. These features distinctly highlight their potential application in environments demanding both robustness and flexibility such as aerospace and automotive industries.

The memristors' high thermal stability is attributed to the crystal structure of the MoS$_{2-x}$O$_x$ even after extensive oxidation, maintaining integrity at temperatures up to 800 °C in high-resolution transmission electron microscopy (HRTEM) tests. Further experimental investigations demonstrated that the switching mechanism is primarily induced by the migration of oxygen ions facilitating resistance changes, while ensuring minimal structural alteration within the material.

Implications and Future Directions

This research provides a promising trajectory for enhancing the practicality and reliability of memristor technology in advanced computing and data storage, particularly under demanding conditions. The findings suggest potential integrations of these memristors in devices requiring high-density memory and embedded computing capacities in harsh environments.

From a theoretical perspective, the demonstration of enhanced device properties through precise material engineering of vdW heterostructures lays the groundwork for further exploration into the customization of electronic device characteristics. This could entail manipulating various 2D materials to further improve memristive performance, longevity under environmental stresses, and integration with complementary metal-oxide-semiconductor (CMOS) technology.

Looking forward, future research could explore scaling the production of these 2D material memristors for commercial applications, fine-tuning the flexibility and stability to align with emerging industry standards. The use of alternative 2D materials or layered combinations may also be explored to enhance the thermal and mechanical properties further, which can widen the application spectrum of memristors in next-generation electronics. The general methodology of employing atomically precise material stacking offers a versatile platform that could extend beyond memristors to other electronic components, fuel innovations in heterogeneous material integration and electronic packaging fields.