vdW Heterostructures for Optical Detection (HEROD)

Name of applicant

Christian Frydendahl


DKK 350,000



Type of grant

Internationalisation Fellowships


The project aims to study how the 2D material graphene can be utilised for ultra-broadband photodetection applications. In particular we will study how the optical properties of graphene can be enhanced by encapsulating it in the complementary 2D material hexagonal boron nitride (hBN), using van der Waals (vdW) force stacking techniques. Encapsulating graphene in this way ensures its highest possible performance, and ensures long-time device stability. Secondly, we will study how such vdW stacked devices can be improved with self-organised metallic nanostructures known as percolation films. These nanostructures can be easily fabricated, and host plasmonic optical field enhancement for many different optical frequencies - ideal for broadband photodetection applications.


Current optical detector technologies rely on using semiconductor materials with different bandgap energies that match the optical wavelength range of interest. This makes it impossible to make a single ultra-broadband photodetector that can cover both the visible and infrared spectral region. Graphene however has a gapless and linear dispersion relation near its Fermi level. This means that graphene can absorb light over a very broad spectral range, from visble to infrared wavelengths. This allows for optical detection in these regimes with a single detector. This could enable new spectral imaging techniques for use in bio- and molecular sensing applications. Secondly, 2D material detectors are by their nature very thin, and easy to integrate in various systems were size is important.


We will utilise a dry visco-elastic polymer transfer technique. By using the correct polymers and heating, it is possible to mechanically pick up exfoliated flakes of graphene or hBN, and then drop the flakes off in a specific position. Like this, it is possible to stack different 2D materials together vertically to create vdW bonded heterostructures. From this, we can make a stack of hBN/graphene/hBN, encapsulating the graphene to protect it from environmental factors, which might lower its electronic performance. After making such stacks, we will study the optical absorption of the middle graphene layer, and try to enhance it via plasmonic nanostructures that will serve to focus light down to the nanoscale, where it can more efficiently couple to the extremely thin graphene.

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