Two-dimensional (2-D) materials are of tremendous interest to integrated photonics given their singular optical characteristics spanning light emission, modulation, saturable absorption, and nonlinear optics. To harness their optical properties, these atomically thin materials are usually attached onto prefabricated devices via a transfer process. In this paper, we present a new route for 2-D material integration with planar photonics. Central to this approach is the use of chalcogenide glass, a multifunctional material which can be directly deposited and patterned on a wide variety of 2-D materials and can simultaneously function as the light guiding medium, a gate dielectric, and a passivation layer for 2-D materials. Besides claiming improved fabrication yield and throughput compared to the traditional transfer process, our technique also enables unconventional multilayer device geometries optimally designed for enhancing light-matter interactions in the 2-D layers. Capitalizing on this facile integration method, we demonstrate a series of highperformance glass-on-graphene devices including ultra-broadband on-chip polarizers, energyefficient thermo-optic switches, as well as graphene-based mid-infrared (mid-IR) waveguideintegrated photodetectors and modulators.

Tunneling triboelectrification of chemical vapor deposited monolayer MoS2 has been characterized at nanoscale with contact-mode atomic force microscopy (AFM) and Kelvin force microscopy (KFM). Although charges can be trapped on insulators like SiO2 by conventional triboelectrification, triboelectric charges tunneling through MoS2 and localized at the underlying substrate exhibit more than two orders of magnitude longer lifetime. Their polarity and density can be modified by triboelectric process with various bias voltages applied to Pt-coated AFM tips, and the saturated density is almost 30 times higher than the reported result of SiO2. Thus, the controllable tunneling triboelectric properties of MoS2 on insulating substrates can provide guidance to build a new class of two-dimensional (2D) MoS2-based nanoelectronic devices.

This work demonstrates a large area process for atomically thin 2D semiconductors to unlock the technological upscale required for their commercial uptake. The new atomic layer deposition (ALD) and conversion technique yields large area performance uniformity and tunability. Like graphene, 2D Transition Metal Dichalcogenides (TMDCs) are prone to upscaling challenges limiting their commercial uptake. They are challenging to grow uniformly on large substrates and to transfer on alternative substrates while they often lack in large area electrical performance uniformity. The scalable ALD process of this work enables uniform growth of 2D TMDCs on large area with independent control of layer thickness, stoichiometry and crystallinity while allowing chemical free transfers to application substrates. Field effect transistors (FETs) fabricated on flexible substrates using the process present a field effect mobility of up to 55 cm2/Vs, subthreshold slope down to 80 mV/dec and on/off ratios of 107. In addition, non-volatile memory transistors using ferroelectric FETs (FeFETs) operating at ±5 V with on/off ratio of 107 and a memory window of 3.25 V are demonstrated. These FeFETs demonstrate state-of-the-art performance with multiple state switching, suitable for one-transistor non-volatile memory and for synaptic transistors revealing the applicability of the process to flexible neuromorphic applications.

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Abstract:The technology behind rewritable optical disks offers a new switching paradigm for metamaterials. A switch comprising resonant plasmonic metamaterial and electro-optic chalcogenide glass layers provides 75% optical transmission modulation in a device of subwavelength thickness. Photonic metamaterials -nanostructured media with extraordinary properties not found in nature -have recently become the subject of intense investigation for revolutionary applications across major industries from telecommunications and defence to renewable energy and healthcare.Here, we demonstrate a new dimension in metamaterial functionality: an active switching device achieved through the hybridization of metamaterials with functional electro-optic materials. For this purpose we have exploited the active properties of chalcogenide glasses. These phase-change media, which can be reversibly switched between amorphous and crystalline states on a nanosecond timescale by optical and electronic excitations, underpin the functionality of today's re-writable optical data storage media and are set to form the basis of nextgeneration electronic memory chips known as phase change memory.We studied an electro-optical device consisting of a planar metamaterial array, with resonant transmission features, sandwiched between a thin layer of Ga:La:S chalcogenide glass and a supporting silicon nitride membrane (Figs. 1a, b). The functionality of the asymmetric split-ring metamaterial structure, milled by focused ion beam in a gold film, depends on so-called 'trapped (closed) mode' plasmon resonant excitations.An electric signal to control the device was applied between the structured gold layer and an electrode on the surface of the chalcogenide film. Switching the structural phase of the Ga:La:S from amorphous to crystalline (a transition that can be reversed by another electrical or optical input) leads to a strong change in the refractive index of the glass layer (Δn ~ 0.35). This in turn drives a blue shift of ~130 nm in the device's resonant transmission spectrum. The device that is only 370 nm thick provides a 75% electro-optically controlled resonant transmission modulation at a wavelength of 1200 nm (Fig. 1c).We show that by changing the structural parameters of the metamaterial array the resonant frequency of the device may be shifted throughout the visible and near-infrared parts of the spectrum.

Aqueous zinc ion batteries are promising candidates for large-scale energy storage. Supramolecular gels have been widely used due to their self-assembly, controllability and biocompatibility. Here, a gelator was successfully synthesised...

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