Integration Of Two-dimensional Materials Research Articles

Designing spintronic devices in two-dimensional γ-graphyne: from ultrafast spin dynamics to logic applications

The integration of two-dimensional materials into spintronics represents a frontier in the development of novel computational devices. In this work, by utilizing ab initio many-body theory, we investigate the spin dynamics within the Co-doped γ-graphyne structure, with a particular emphasis on the role of cobalt atoms as magnetic centers. The result reveals that each cobalt atom on the γ-graphyne hosts states with enough spin-density localization to facilitate both local spin flips and global spin transfers. The spin-dynamic processes in our study are characterized by ultrafast time scales and high fidelities, demonstrating efficient spin control in the system. Building upon these spin-dynamic processes, we theoretically construct a spin-based Reset-Set latch, thus demonstrating the feasibility of sophisticated logic operations in our system. Such spin-based devices exhibit the advantages of nano-spintronics over conventional-electronic approaches, offering lower energy consumption, faster operational speeds, and greater potential for miniaturization. The results highlight the efficacy of γ-graphyne nanoflakes doped with cobalt atoms as spin-information processing units, signifying a pivotal advancement in the incorporation of graphyne-based materials into sophisticated spintronic devices. This research paves the way for their application in areas such as data storage, quantum computing, and the development of complex logic-processing architectures.

Tunable electronic and optical properties of h-BP/MoS2 van der Waals heterostructures toward optoelectronic applications

The integration of two-dimensional materials (2D) into van der Waals heterostructures (vdWHs) is widely recognized as an effective strategy for the development of multifunctional devices. This study aims to construct stable ultrathin 2D vdWHs using h-BP and MoS2 monolayers, and analyze the impact of strain on the electronic properties of h-BP/MoS2 vdWHs, with a specific focus on the mechanism of biaxial strain regulation. The h-BP/MoS2 vdWHs demonstrate the type II band alignment and possess direct bandgap, which can be effectively controlled through appropriate application of biaxial strain. The power conversion efficiency (PCE) can reach 21.85 % achieved suggests that the material under consideration has potential as a suitable candidate for 2D excitonic solar cells. The observed decrease in effective mass for both electrons and holes implies an enhanced carrier mobility, thereby facilitating the utilization of h-BP/MoS2 vdWHs in the development of high-efficiency excitonic solar cells. These findings indicate that the h-BP/MoS2 vdWHs possess the capability to serve as a reconfigurable system in the construction of highly efficient solar cells.

The Integration of Two-Dimensional Materials and Ferroelectrics for Device Applications.

In recent years, there has been growing interest in functional devices based on two-dimensional (2D) materials, which possess exotic physical properties. With an ultrathin thickness, the optoelectrical and electrical properties of 2D materials can be effectively tuned by an external field, which has stimulated considerable scientific activities. Ferroelectric fields with a nonvolatile and electrically switchable feature have exhibited enormous potential in controlling the electronic and optoelectronic properties of 2D materials, leading to an extremely fertile area of research. Here, we review the 2D materials and relevant devices integrated with ferroelectricity. This review starts to introduce the background about the concerned themes, namely 2D materials and ferroelectrics, and then presents the fundamental mechanisms, tuning strategies, as well as recent progress of the ferroelectric effect on the optical and electrical properties of 2D materials. Subsequently, the latest developments of 2D material-based electronic and optoelectronic devices integrated with ferroelectricity are summarized. Finally, the future outlook and challenges of this exciting field are suggested.

Few-Layer Graphene Integrated Tilted Fiber Grating For All-Optical Switching

Recently, the integration of two-dimensional materials with optical fibers has opened up a great opportunity to develop all-fiber signal-processing devices. Graphene is an ideal material for all-optical signal processing via thermal-optic effect because of its high electrical and thermal conductivity, as well as broadband light-matter interactions with fast responses. Herein, we report the achievement of all-optical switching with fast response by integrating few-layer graphene onto a tilted fiber Bragg grating (TFBG) inscribed in a reduced-diameter fiber. Relying on graphene's decent photothermal effect, the transmission spectrum of the TFBG could be all-optically modulated by tuning the incident pump power. The all-optical switch can consequently operate at a series of wavelengths owing to the TFBG's comb-like resonances. The reduced diameter of the graphene-integrated TFBG and the pump at its resonant wavelength promise the all-optical switch to have a fast-dynamic response of around 1 μs and an extinction ratio exceeding 13 dB. This compact device with graphene integration has the potentials to be integrated into all-fiber system to extend the functions of all-optical signal processing.

2D-material-integrated whispering-gallery-mode microcavity

Optical microcavities, which support whispering gallery modes, have attracted tremendous attention in both fundamental research and potential applications. The emerging of two-dimensional materials offers a feasible solution to improve the performance of traditional microcavity-based optical devices. Besides, the integration of two-dimensional materials with microcavities will benefit the research of heterogeneous materials on novel devices in photonics and optoelectronics, which is dominated by the strongly enhanced light–matter interaction. This review focuses on the research of heterogeneous two-dimensional-material whispering-gallery-mode microcavities, opening a myriad of lab-on-chip applications, such as optomechanics, quantum photonics, comb generation, and low-threshold microlasing.

Manipulation of extinction features in frequency combs through the usage of graphene

Lately, the integration of two-dimensional materials into semiconductor devices has allowed the modification of their effective index by simply applying a modest voltage (between 0 and 3 volts). In this work, we present a device composed of two evanescently coupled silicon microring resonators where both rings have a graphene layer on top. This design is aimed to produce frequency combs with transmission characteristics controlled upon voltage application to the graphene layer. We numerically analyze the device response as a function of the incident wavelength and applied voltage. The results showed a low input intensity (0.6 GW/cm2) needed and a rapid response time (0.1 μs), in comparison to devices controlled by heat injection.

CMOS-Compatible WS2-Based All-Optical Modulator

Two-dimensional materials are compatible with silicon complementary metal-oxide semiconductor processes. As such, the integration of two-dimensional materials with silicon-based semiconductors could lead to an amalgamation of the beneficial properties of both silicon and the two-dimensional material thereby facilitating improved performance. Single-layer transition metal dichalcogenide materials like MoS2, MoTe2 and WS2 are characterized by direct band gaps and possess high emission efficiencies. These materials are, therefore, perfectly suited for ameliorating the optical emission inadequacies of silicon-based-materials. In this study, we integrate WS2 with a silicon-based silicon-nitride waveguide to modulate a 532-nm pump light source, and successfully modulate and amplify an optical signal at 640 nm. Compared to other modulators based on two-dimensional materials, e.g., graphene, the proposed WS2-based modulator theoretically incurs lower losses and exhibits higher contrast levels and signal-to-noise ...

(Invited) Excellent Wetting Behavior of Yttria on 2D Materials

The integration of two-dimensional materials into nanoelectronic devices requires contact with high-κ dielectric. For better performance, it is indispensable to grow uniform and conformal dielectric materials. In this paper, we show the excellent wetting behavior of yttrium oxide (yttria, Y2O3) thin films on graphene using several interface and surface science techniques. The uniformity of the Y2O3 was characterized using scanning tunneling microscopy, atomic force microscopy, transmission electron microscopy, and low energy ion scattering. Photoemission was used to investigate the surface chemistry and the charge doping level of graphene by evaluating the C 1s core level. Furthermore, the favorable wetting behavior of yttria is exploited as an effective buffer layer for atomic layer deposition of Al2O3 on non-functionalized graphene surface.