Van der Waals integration enables advanced photonic applications from 2D materials to 3D crystals

(Nanowerk Highlights) Van der Waals integration (vdW) refers to a physical assembly strategy originally applied in the two-dimensional (2D) materials and nanotechnology community to construct vdW heterostructures and electronic devices. This method circumvents the fundamental limits of lattice matching and process compatibility in heteroepitaxy by utilizing transfer films, without the need for expensive instruments or lengthy development processes. It also has an unprecedented degree of freedom in constructing artificially layered vdW structures regardless of 2D material composition or crystal parameters.

Recent years, however, have witnessed exciting advances in applying vdW integration to photonics and optoelectronic applications, not only of 2D materials but also of exfoliated freestanding 3D nanomembranes (Fig. 1).

Recent advances in 2D materials-assisted epitaxy and layer lifting techniques have enabled the collection of functional single-crystalline three-dimensional (3D) thin films that can also be exfoliated from the parent substrate into freestanding thin films like 2D materials, with an arbitrarily defined vdW interface. artificially for photonic vdW integration.

Nanomembranes with a wide range of optical functions, such as electro-optical thin-film lithium niobate, group III-V optical gain media such as GaAs, and AlN piezoelectric films, can be easily transferred to arbitrarily prefabricated photonic structures such as optical waveguides, micro-resonators, and metasurface for massive new photonics applications. Figure 1. Freestanding 2D and 3D nanomembranes for van der Waals photonic integration. (Image courtesy of the researchers)

In a recent paper published in Natural Review Ingredients (“Photonic van der Waals integration of 2D materials onto 3D nanomembranes”), an international team of researchers from the United States, Singapore, and South Korea have presented a comprehensive review article outlining recent advances in photonic vdW integration.

The 2D and 3D vdW building blocks available today are comprehensively cataloged, with detailed discussions from thin film preparation to device implementation. Practical challenges preventing the field from migrating to full-fledged technologies are outlined, including scalable nanomembrane production and high-quality layer transfer. The opportunities that await are highlighted also for advanced hetero-integrated photonics, vdW meta-photonics, polariton nanophotonics, and flexible and bio-compatible optoelectronic applications.

In addition, the exfoliation of these single crystal nanomembranes has also enabled the reuse of expensive substrates to greatly reduce the cost of non-silicon materials such as GaAs, GaN, InP to drive further commercialization for photonic and nano-electronic integrated circuits. . Figure 2. Basic attributes of van der Waals photonic films. (Image courtesy of the researchers)

Because a photonic vdW integration approach can enable previously inaccessible device layouts and hybrid heterostructures by tinkering around 2D and 3D vdW thin-film building blocks, the authors envision record-breaking new hetero-integrated photonic devices and exotic nanophotonic physics hatching from vdW interface mix dimensions. Provided by the University of Washington at St. Louis