Integration of Single Photon Emitters in 2D Layered Materials with a Silicon Nitride Photonic Chip

Photonic integrated circuits (PICs) enable miniaturization of optical quantum circuits because several optic and electronic functionalities can be added on the same chip. Single photon emitters (SPEs) are central building blocks for such quantum circuits and several approaches have been developed to interface PICs with a host material containing SPEs. SPEs embedded in 2D transition metal dichalcogenides have unique properties that make them particularly appealing as PIC-integrated SPEs. They can be easily interfaced with PICs and stacked together to create complex heterostructures. Since the emitters are embedded in a monolayer there is no total internal reflection, enabling very high light extraction efficiencies without the need of any additional processing to allow efficient single photon transfer between the host and the underlying PIC. Arrays of 2D-based SPEs can moreover be fabricated deterministically through STEM patterning or strain engineering. Finally, 2D materials grown with high wafer-scale uniformity are becoming more readily available, such that they can be matched at the wafer level with underlying PICs. Here we report on the integration of a WSe$_{2}$ monolayer onto a Silicon Nitride (SiN) chip. We demonstrate the coupling of SPEs with the guided mode of a SiN waveguide and study how the on-chip single photon extraction can be maximized by interfacing the 2D-SPE with an integrated dielectric cavity. Our approach allows the use of optimized PIC platforms without the need for additional processing in the host material. In combination with improved wafer-scale CVD growth of 2D materials, this approach provides a promising route towards scalable quantum photonic chips

Refractive uses of layered and two-dimensional materials for integrated photonics

The scientific community has witnessed tremendous expansion of research on layered (i.e. two-dimensional, 2D) materials, with increasing recent focus on applications to photonics. Layered materials are particularly exciting for manipulating light in the confined geometry of photonic integrated circuits, where key material properties include strong and controllable light-matter interaction, and limited optical loss. Layered materials feature tunable optical properties, phases that are promising for electro-optics, and a panoply of polymorphs that suggest a rich design space for highly-nonperturbative photonic integrated devices based on phase-change functionality. All of these features are manifest in materials with band gap above the photonics-relevant near-infrared (NIR) spectral band ($\sim$ 0.5 - 1 eV), meaning that they can be harnessed in refractive (i.e. non-absorptive) applications.Comment: review paper. ACS Photonics (2020

The Renaissance of Black Phosphorus

One hundred years after its first successful synthesis in the bulk form in 1914, black phosphorus (black P) was recently rediscovered from the perspective of a two-dimensional (2D) layered material, attracting tremendous interest from condensed matter physicists, chemists, semiconductor device engineers and material scientists. Similar to graphite and transition metal dichalcogenides (TMDs), black P has a layered structure but with a unique puckered single layer geometry. Because the direct electronic band gap of thin film black P can be varied from 0.3 to around 2 eV, depending on its film thickness, and because of its high carrier mobility and anisotropic in-plane properties, black P is promising for novel applications in nanoelectronics and nanophotonics different from graphene and TMDs. Black P as a nanomaterial has already attracted much attention from researchers within the past year. Here, we offer our opinions on this emerging material with the goal of motivating and inspiring fellow researchers in the 2D materials community and the broad readership of PNAS to discuss and contribute to this exciting new field. We also give our perspectives on future 2D and thin film black P research directions, aiming to assist researchers coming from a variety of disciplines who are desirous of working in this exciting research field.Comment: 23 pages, 6 figures, perspective article, appeared online in PNA

Waveguide-coupled light emitting devices made of 2D materials

Optical information processing using photonic integrated circuits is a key goal in the field of nanophotonics. Extensive research efforts have led to remarkable progress in integrating active and passive device functionalities within one single photonic circuit. Still, to date, one of the central components - i.e. light sources - remain a challenge to be integrated. Here, we demonstrate waveguide-coupled electrically driven light emitters in an on-chip photonics platform based on 2D materials. We combine light-emitting devices (LEDs), based on exciton recombination in transition metal dichalcogenides (TMDs), with hexagonal boron nitride (h-BN) photonic waveguides in a single van der Waals (vdW) heterostructure. Waveguide-coupled light emission is achieved by sandwiching the LED between two h-BN slabs and patterning the complete vdW stack into a photonic structure. Our demonstration of on-chip light generation and waveguiding is a key component for future integrated vdW optoelectronics

Dispersing and Depositing MoSe2 onto Metal, Insulating, and Semiconducting Substrates via Voltage-Controlled Deposition Technique

In today’s world, consumer electronics are getting smaller than ever. These reductions in size are preceded by advancements in electronic materials engineering and related fields. The need for materials that have various properties and are suitable for applications also necessitated research on different materials. Growing research in the applications of graphene led the way to the discovery of materials that have similar properties to graphene. In this way, the transition metal di-chalcogenides (TMDCs) came into use for electrical engineering. Techniques are required to put TMDCs into application, however here we are going to explain the vital focus of our research which is to discuss a successful method of depositing a solution of dispersed MoSe2 using the voltage-controlled deposition technique. Here we are focusing mainly to find an inexpensive, simple and efficient method to deposit the TMDCs onto substrates. Initially powdered MoSe2 is dispersed in n-Methyl Pyrrolidone (NMP), and the dispersed solution is deposited onto different substrates. The different substrates that we used in this project were conducting substrate (Al foil), semi-conducting substrate (Si wafer), and insulating substrates (Glass, SiO2, PMMA). At first, MoSe2 was dispersed in NMP using the tip sonication method. Later, by using the voltage-controlled deposition technique the dispersed solution is deposited onto the aforementioned substrates. The final stage of the process is to analyze the deposition of MoSe2 onto the substrates and etched substrates; we used Scanning Electron Microscopy and Raman Spectroscopy. Through this research we have examined how MoSe2 is dispersed well in NMP, and deposited onto bare and etched substrates as may be useful for future device building surface

A Review on Mechanics and Mechanical Properties of 2D Materials - Graphene and Beyond

Since the first successful synthesis of graphene just over a decade ago, a variety of two-dimensional (2D) materials (e.g., transition metal-dichalcogenides, hexagonal boron-nitride, etc.) have been discovered. Among the many unique and attractive properties of 2D materials, mechanical properties play important roles in manufacturing, integration and performance for their potential applications. Mechanics is indispensable in the study of mechanical properties, both experimentally and theoretically. The coupling between the mechanical and other physical properties (thermal, electronic, optical) is also of great interest in exploring novel applications, where mechanics has to be combined with condensed matter physics to establish a scalable theoretical framework. Moreover, mechanical interactions between 2D materials and various substrate materials are essential for integrated device applications of 2D materials, for which the mechanics of interfaces (adhesion and friction) has to be developed for the 2D materials. Here we review recent theoretical and experimental works related to mechanics and mechanical properties of 2D materials. While graphene is the most studied 2D material to date, we expect continual growth of interest in the mechanics of other 2D materials beyond graphene