19 April 2017 Integrated graphene photodetector based on a gate- controlled pn- junction (Conference Presentation)
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Abstract
The integration of electrical and optical components on a single chip, favourable silicon, is a major goal in research. Thereby, a bottleneck is the integration of active and passive optical elements. Graphene, with its electrically tuneable absorption and ultrafast photoresponse, is a promising candidate to move a step closer towards high-speed on-chip integration. We fabricated a dual-gate tuneable pn-junction graphene phototdetector to investigate the relevant conversion mechanisms. The photodector is integrated on a silicon slot waveguide, which has twofold function. First, the two silicon strips of the slot waveguide are utilized as dual gate electrodes to create an electrically controllable pn-junction in the graphene. Second, the slot waveguide design allows confinement of light in subwavelength dimension. The confined light is directly absorbed in the slot between the n- and p-doped regions. At zero bias the conversion is dominated by the photo-thermoelectric effect, where we achieved a responsivity of 35 mA/W. While by applying a low bias of 300 mV, the responsivity increased to 76 mA/W due to an additional photoconductive contribution. The photoresponse of photodetectors based on the photo-thermoelectric effect arises from hot electrons, rather than lattice heating. Therefore, we could demonstrate that our graphene integrated photodetector based on a tuneable pn-junction reaches a setup-limited 3dB-bandwidth of 65 GHz, which is the highest value reported for a graphene-based phototedetector.
Conference Presentation
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Simone Schuler, Simone Schuler, Daniel Schall, Daniel Schall, Daniel Neumaier, Daniel Neumaier, Lukas Dobusch, Lukas Dobusch, Ole Bethge, Ole Bethge, Benedikt Schwarz, Benedikt Schwarz, Michael Krall, Michael Krall, Thomas Mueller, Thomas Mueller, "Integrated graphene photodetector based on a gate- controlled pn- junction (Conference Presentation)", Proc. SPIE 10106, Integrated Optics: Devices, Materials, and Technologies XXI, 1010611 (19 April 2017); doi: 10.1117/12.2251338; https://doi.org/10.1117/12.2251338
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