New type of graphene photodetector could enable low-cost cameras for self-driving cars and robots

An international team of researchers recently reported its success in creating a new type of graphene-based photodetector.

The team integrated three concepts to achieve the new device: metallic plasmonic antennas, ultra sub-wavelength waveguiding of light and graphene photodetection. Specifically, the 2D-material hexagonal boron nitride was used as the waveguide for hyperbolic phonon polaritons, which can highly confine and guide mid-infrared light at the nanoscale. By carefully matching the nano-antenna with the phonon polariton waveguide, they efficiently funnel incoming light into a nanoscale graphene junction. By using this approach, they were able to overcome intrinsic limitations of graphene, such as its low absorption and its small photoactive region near the junction.

By doing this, the authors demonstrated the technological relevance of such a detector. They were able to report a record performance of the device working at operating at room temperature by obtaining a very high sensitivity (noise-equivalent-power) of 82 pW/Hz1/2, an extremely high speed, by showing a setup-limited rise time of 17 nanoseconds, and a high dynamic range. Also, they showed that it operates without bias, which leads to negligible power consumption and dark-current, outperforming current mid-infrared graphene and commercial detectors in various aspects.

All of these performance features combined make this novel photodetector a remarkable platform for low-cost infrared cameras, as the materials used in its fabrication are CMOS compatible at the waferscale level. The system has proven to fulfill the ongoing trend of decreasing the size, weight and power consumption (SWaP) of infrared imaging systems.

The work was carried out within the framework of the Graphene Flagship Core 2 and Core 3 that enforces graphene-based technology from the lab to the market.

The work was carried out by ICFO researchers Sebastián Castilla, Varun-Varma Pusapati, Khannan Rajendran and Dr. Seyoon Kim, led by ICREA Prof. at ICFO Frank Koppens and former ICFO scientist Dr. Klaas-Jan Tielrooij (from ICN2), in collaboration with researchers Ioannis Vangelidis and Prof. Elefterios Lidorikis from University of Ioannina and with scientists from CIC NanoGUNE BRTA, Massachusetts Institute of Technology (MIT), CSIC-Universidad de Zaragoza and the National Institute for Material Sciences.