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Graphene and two-dimensional materials (2DM) remain an active field of research in science and engineering over 15 years after the first reports of 2DM. The vast amount of available data and the high performance of device demonstrators leave little doubt about the potential of 2DM for applications in electronics, photonics and sensing. So where are the integrated chips and enabled products? We try to answer this by summarizing the main challenges and opportunities that have thus far prevented 2DM applications. Graphene and related two-dimensional (2D) materials have remained an active field of research in science and engineering for over fifteen years. Here, the authors investigate why the transition from laboratories to fabrication plants appears to lag behind expectations, and summarize the main challenges and opportunities that have thus far prevented the commercialisation of these materials.

Nanoelectronic devices based on 2D materials are far from delivering their full theoretical performance potential due to the lack of scalable insulators. Amorphous oxides that work well in silicon technology have ill-defined interfaces with 2D materials and numerous defects, while 2D hexagonal boron nitride does not meet required dielectric specifications. The list of suitable alternative insulators is currently very limited. Thus, a radically different mindset with respect to suitable insulators for 2D technologies may be required. We review possible solution scenarios like the creation of clean interfaces, production of native oxides from 2D semiconductors and more intensive studies on crystalline insulators. The lack of scalable, high-quality insulators is a major problem hindering the progress on electronic devices built from 2D materials. Here, the authors review the current state-of-the-art and the future prospects of suitable insulators for 2D technologies.

Integrating two-dimensional (2D) materials into semiconductor manufacturing lines is essential to exploit their material properties in a wide range of application areas. However, current approaches are not compatible with high-volume manufacturing on wafer level. Here, we report a generic methodology for large-area integration of 2D materials by adhesive wafer bonding. Our approach avoids manual handling and uses equipment, processes, and materials that are readily available in large-scale semiconductor manufacturing lines. We demonstrate the transfer of CVD graphene from copper foils (100-mm diameter) and molybdenum disulfide (MoS 2 ) from SiO 2 /Si chips (centimeter-sized) to silicon wafers (100-mm diameter). Furthermore, we stack graphene with CVD hexagonal boron nitride and MoS 2 layers to heterostructures, and fabricate encapsulated field-effect graphene devices, with high carrier mobilities of up to 4520 cm 2 V − 1 s − 1 . Thus, our approach is suited for backend of the line integration of 2D materials on top of integrated circuits, with potential to accelerate progress in electronics, photonics, and sensing. The existing integration approaches for 2D materials often degrade material properties and are not compatible with industrial processing. Here, the authors devise an adhesive wafer bonding strategy to transfer and stack monolayers, suitable for back end of the line integration of 2D materials.

This article reviews the potential of graphene and related two-dimensional (2D) materials for applications in micro- and nanoelectronics. In addition to graphene, special emphasis is placed on transition metal dichalcogenides (TMDs). First, we discuss potential solutions for application-scale material growth, in particular chemical vapor deposition. We describe challenges for electrical contacts and dielectric interfaces with 2D materials. The device-related sections in this review first weigh the pros and cons of semi-metal graphene as a field-effect transistor (FET) channel material for logic and radio frequency applications. This is followed by an introduction to alternate graphene switch concepts that utilize the particular properties of the material, namely tunnel FETs, vertical devices, and bilayer pseudospin FETs. The final section is dedicated to semiconducting TMDs and their integration in FETs using the examples of n-type molybdenum disulfide (MoS2) and p-type tungsten diselenide (WSe2).

The use of organic, oxide and low-dimensional materials in field-effect transistors has now been studied for decades. However, properly reporting and comparing device performance remains challenging due to the interdependency of multiple device parameters. The interdisciplinarity of this research community has also led to a lack of consistent reporting and benchmarking guidelines. Here we propose guidelines for reporting and benchmarking key field-effect transistor parameters and performance metrics. We provide an example of this reporting and benchmarking process using a two-dimensional semiconductor field-effect transistor. Our guidelines should help promote an improved approach for assessing device performance in emerging field-effect transistors, helping the field to progress in a more consistent and meaningful way. This Perspective examines the challenges involved in assessing the operation and performance of field-effect transistors based on emerging materials, and provides guidelines for the consistent reporting and benchmarking of the devices.

Advanced operando transmission electron microscopy (TEM) techniques enable the observation of nanoscale phenomena in electronic devices during operation. Here, we investigated lateral memristive devices composed of two dimensional layered MoS 2 with Pd and Ag electrodes. Under external bias voltage, we visualized the formation and migration of Ag conductive filaments (CFs) between the two electrodes, and their complete dissolution upon reversing the biasing polarity. The CFs exhibited a wide range of sizes, from several Ångströms to tens of nanometers, and followed diverse pathways: along the MoS 2 surfaces, within the van der Waals gap between MoS 2 layers, and through the spacing between MoS 2 bundles. Our method enables correlation between current-voltage responses and real-time TEM imaging, offering insights into failed and anomalous switching behaviors, and clarifying the cycle-to-cycle variabilities. Our findings provide solid evidence for the electrochemical metallization mechanism, elucidate the formation dynamics of CFs, and reveal key parameters influencing the switching performance. 2D materials have attracted significant attention for memristor applications, but a complete understanding of the switching mechanisms is still lacking. Here, the authors report an operando electron microscopy study of lateral MoS 2 memristors, showing real-time imaging of the dynamics of Ag conductive filaments during bias voltage cycles.

The commercialization of electronic devices based on graphene has not yet been successful, even 20 years after its first isolation. To this end, the European Commission is supporting research toward establishing a European experimental pilot line for electronic and optoelectronic devices based on graphene and related two-dimensional (2D) materials, namely the Experimental Pilot Line (2D-EPL) project. Here, we report the results obtained during the first and third multi-project wafer (MPW) runs completed at the end of 2022 (MPW run 1) and 2023 (MPW run 3) as an outcome of the 2D-EPL. Test devices were measured across the wafers to assess the device quality and variability before delivering the fabricated dies to the customers. Raman spectroscopy confirmed minimal structural changes in the graphene caused by the fabrication process, while electrical measurements of two different device types verified the device specifications defined in the process design kit. The Experimental Pilot Line (2D-EPL) project has been launched in 2020 by the European Commission to promote the production of 2D (opto-)electronics and sensing devices. Here, the authors report the results and challenges of the first and third multi-project wafer runs completed at the end of 2022 and 2023 as part of the 2D-EPL.

Two-dimensional (2D) materials are considered for numerous applications in microelectronics, although several challenges remain when integrating them into functional devices. Weak adhesion is one of them, caused by their chemical inertness. Quantifying the adhesion of 2D materials on three-dimensional surfaces is, therefore, an essential step toward reliable 2D device integration. To this end, button shear testing is proposed and demonstrated as a method for evaluating the adhesion of 2D materials with the examples of graphene, hexagonal boron nitride (hBN), molybdenum disulfide, and tungsten diselenide on silicon dioxide and silicon nitride substrates. We propose a fabrication process flow for polymer buttons on the 2D materials and establish suitable button dimensions and testing shear speeds. We show with our quantitative data that low substrate roughness and oxygen plasma treatments on the substrates before 2D material transfer result in higher shear strengths. Thermal annealing increases the adhesion of hBN on silicon dioxide and correlates with the thermal interface resistance between these materials. This establishes button shear testing as a reliable and repeatable method for quantifying the adhesion of 2D materials. 2D materials are being investigated for several applications in micro- and nanoelectronics, but their weak adhesion represents a critical challenge for device integration. Here, the authors propose a button shear testing method to evaluate the adhesion forces of various large-area 2D films on SiO 2 and Si 3 N 4 substrates.

Graphene is being increasingly used as an interesting transducer membrane in micro- and nanoelectromechanical systems (MEMS and NEMS, respectively) due to its atomical thickness, extremely high carrier mobility, high mechanical strength, and piezoresistive electromechanical transductions. NEMS devices based on graphene feature increased sensitivity, reduced size, and new functionalities. In this review, we discuss the merits of graphene as a functional material for MEMS and NEMS, the related properties of graphene, the transduction mechanisms of graphene MEMS and NEMS, typical transfer methods for integrating graphene with MEMS substrates, methods for fabricating suspended graphene, and graphene patterning and electrical contact. Consequently, we provide an overview of devices based on suspended and nonsuspended graphene structures. Finally, we discuss the potential and challenges of applications of graphene in MEMS and NEMS. Owing to its unique features, graphene is a promising material for emerging MEMS, NEMS, and sensor applications.

Wireless communications have progressively tapped into higher frequency bands seeking higher bandwidth and integration, opening the door to short-range applications such as data kiosks, wireless chip interconnects, or intra-body networks. Graphene antennas working at terahertz (THz) frequencies are theoretically smaller in size compared to metallic antennas working at the same frequency, pushing the boundaries of integration further. However, such miniaturization ability has not yet been experimentally validated. This study presents the first working THz antenna based on chemical vapor deposited (CVD) monolayer graphene. The antenna, placed on the hexagonal Boron Nitride (hBN) buffer layer, comprises a multi-layer stack of two graphene patches separated by a thin dielectric, resulting in a significantly more efficient antenna than a standard one-layer graphene antenna. The proposed antenna shows a resonance frequency of 250.7 GHz and a gain of -9.5 dB. The miniaturization and frequency tuning capabilities of graphene antennas make the proposed graphene stack patch antenna a valuable asset for 6G short-range communications. Additionally, the proposed graphene stack antenna can be integrated in the back-end-of-line with CMOS manufacturing techniques and applied to future THz communication systems.