Emerging 2D Materials and Devices for the Internet of Things

Information, Sensing and Energy Applications

Li Tao, Deji Akinwande

• Publisher: Elsevier
• Year: 2020
• Print ISBN: 9780128183861
• eBook ISBN: 9780128183878
• Topic: Tecnologia e ingegneria
• Subtopic: Scienza dei materiali

Emerging 2D Materials and Devices for the Internet of Things: Information, Sensing and Energy Applications summarizes state-of-the-art technologies in applying 2D layered materials, discusses energy and sensing device applications as essential infrastructure solutions, and explores designs that will make internet-of-things devices faster, more reliable and more accessible for the creation of mass-market products. The book focuses on information, energy and sensing applications, showing how different types of 2D materials are being used to create a new generation of products and devices that harness the capabilities of wireless technology in an eco-efficient, reliable way.This book is an important resource for both materials scientists and engineers, who are designing new wireless products in a variety of industry sectors.- Explores how 2D materials are being used to create faster and more reliable wireless network solutions- Discusses how graphene-based nanocomposites are being used for energy harvesting and storage applications- Outlines the major challenges for integrating 2D materials in electronic sensing devices

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Two-dimensional materials-based nonvolatile resistive memories and radio frequency switches

Ruijing Ge, Xiaohan Wu, Myungsoo Kim, Jack C. Lee and Deji Akinwande, Microelectronics Research Center, Department of Electrical and Computer Engineering, University of Texas at Austin, Austin, TX, United States

Abstract

In this chapter, we demonstrated the application of two-dimensional (2D) monolayer atomic sheets (transition metal dichalcogenides and hexagonal boron nitride) in nonvolatile resistive memory using metal-insulator-metal vertical structure. These devices can be labeled as “atomristor,” which means the memristor effect in atomically thin nanomaterials. Among 2D memory devices, atomristor stands out due to the atomic thinness of the active layer, low switching voltage, forming-free characteristic, large ON/OFF current ratio, and fast switching speed. In the last section, another major application based on atomristor, monolayer MoS₂-based radio frequency switch will be presented.

Keywords

2D materials; nonvolatile memory; RF switch; transitional metal dichalcogenide; hexagonal boron nitride; flexible electronics

Chapter Outline

Outline

• 1.1 Introduction to two-dimensional nonvolatile resistive memory 1
• 1.2 Two-dimensional materials preparation and memory device fabrication 3
  • 1.2.1 Preparation and characterization of two-dimensional monolayers 3
  • 1.2.2 Fabrication of memory devices 3
• 1.3 Two-dimensional nonvolatile resistive memory 7
  • 1.3.1 Nonvolatile resistive memory based on different device conditions 7
  • 1.3.2 Memory performance 11
• 1.4 Switching mechanics 12
  • 1.4.1 Factors influencing resistive switching 12
  • 1.4.2 Possible switching mechanics based on ab initio simulation 16
• 1.5 MoS₂ radio frequency switches 18
  • 1.5.1 Introduction to radio frequency switch 18
  • 1.5.2 Fabrication and measurement of MoS₂ radio frequency switch 20
  • 1.5.3 MoS₂ radio frequency switch performance 21
• 1.6 Summary 25
• Acknowledgment 25
• References 25

1.1 Introduction to two-dimensional nonvolatile resistive memory

Worldwide advancement in wireless communication and connectivity systems for Internet-of-things (IoT) has resulted in an ever-increasing demand for memories [1]. Over the past few decades, tremendous efforts have been made to develop high-density, low-cost, and nonvolatile memory devices [2]. Compared with volatile memory such as dynamic random access memory and static random access memory dissipating both dynamic and static energy, nonvolatile memory with zero-static power is attractive considering energy efficiency. One representative nonvolatile memory, Flash, has the largest solid-state nonvolatile memory market [3]. However, since it faces its scalability limit due to short channel effect and channel boosting leakage, researchers have been working on some emerging memories to meet the new requirements [4]. One emerging memory alternative is phase-change memory (PCM) based on phase-change materials, which can be reversibly switched between crystalline and amorphous phases through thermal processes, resulting in a change in resistivity. However, PCM is primarily limited due to thermal proximity effects.

Another major emerging nonvolatile memory candidate, resistive random-access memory (RRAM), does not depend on thermal processes and has lower power consumption compared with PCM [5]. Conventional RRAM structure is simply an oxide material sandwiched between metal electrodes, called metal-insulator-metal (MIM) structure. It is worthwhile to notice that RRAM has not only simple structure and materials, but also low operating voltage, low energy consumption, high operating speed, high density, long retention, and wide-range state modulation. RRAM works based on nonvolatile resistive switching (NVRS) between a high-resistance state (HRS) and a low-resistance state (LRS). The switching event from HRS to LRS is called the “SET” process, while the transition from LRS to HRS is called the “RESET” process. Usually the fresh samples require a higher voltage than SET to trigger on the resistive switching behavior and this activation step is called “forming” process. The resistive switching can be generally classified into two modes: unipolar and bipolar. As for unipolar, SET/RESET can occur at the same bias polarity, while bipolar means that the SET/RESET requires opposite bias polarity.

To continue scaling and reducing cell size, our future toward high-density memory would be made up of cells with several atoms or a cluster of molecules. Thus two-dimensional (2D) materials are promising candidates to overcome vertical scaling obstacle in NVRS [6,7]. Recently, NVRS has been observed in various multilayer 2D materials including graphene oxide, partially degraded black phosphorus, functionalized MoS₂ and composites, transition metal dichalcogenide (TMD)-based hybrids and multilayer hexagonal boron nitride (h-BN) [7–12]. However, it was believed that NVRS phenomenon was not accessible in single-layer atomic sheets [7,13] due to excessive leakage current that is known to prevent nanometer scaling in conventional oxide-based vertical MIM configuration. While Sangwan et al. discovered that grain boundaries in single-layer MoS₂ can produce resistive switching based on planar structures and it has been attributed to the defect migration at certain grain boundaries [14]. However, the planar structure without three-dimensional (3D) stacking ability has limitation of low integration density.

In this chapter, we demonstrated the application of 2D monolayer atomic sheets (TMDs and h-BN) in nonvolatile resistive memory using MIM vertical structure. These devices can be labeled as “atomristor,” which means the memristor effect in atomically thin nanomaterials. Among 2D memory devices, atomristor stands out due to the atomic thinness of the active layer, low switching...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• List of contributors
• 1. Two-dimensional materials-based nonvolatile resistive memories and radio frequency switches
• 2. Two-dimensional materials-based radio frequency wireless communication and sensing systems for Internet-of-things applications
• 3. Graphene electronic tattoo sensors for point-of-care personal health monitoring and human–machine interfaces
• 4. Transition metal dichalcogenides as ultrasensitive and high-resolution biosensing nodes
• 5. Nanophotonics and optoelectronics based on two-dimensional MoS2
• 6. Graphene-based anode materials for lithium-ion batteries
• 7. Two-dimensional materials as photoelectrodes in water reduction devices for energy applications
• 8. Two-dimensional Xenes and their device concepts for future micro- and nanoelectronics and energy applications
• 9. Piezoelectric one- to two-dimensional nanomaterials for vibration energy harvesting devices
• 10. Nanocomposite materials for nano-electronic-based Internet of things sensors and energy device signaling
• 11. Prospects and challenges in low-dimensional materials and devices for Internet of things
• Index