Highly polarization-sensitive, broadband, low dark current, high responsivity graphene-based photodetector utilizing a metal nano-grating at telecommunication wavelengths
Elham Khosravian, Hamid Reza Mashayekhi, Ali Farmani
Abstract
Recent advances in graphene-based photodetectors have demonstrated the feasibility of utilizing graphene as a fantastic material for the development of future high-performance photodetectors. In this paper, a high-performance graphene-based photodetector is proposed with plasmonic structure by employing a single graphene layer, periodic metal nano-grating, and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">S</mml:mi> <mml:mi mathvariant="normal">i</mml:mi> </mml:mrow> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">S</mml:mi> <mml:mi mathvariant="normal">i</mml:mi> </mml:mrow> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">O</mml:mi> </mml:mrow> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:math> substrate. The plasmonic coupling phenomena between graphene and the metal nano-grating can cause absorption enhancement in this structure. The proposed structure has almost perfect absorption at the telecommunication wavelength (1.55 µm), and its optical response shows a polarization-sensitive characteristic in the spectral range from 1 µm to 2.1 µm. Moreover, the electrical characterization and the dynamic response of this structure are obtained. Based on simulation results, the proposed structure under 0.5 mW incident optical power and at a wavelength of 1.55 µm exhibits a low dark current on the order of about 0.001 mA, maximum photocurrent of 0.81 mA, and responsivity of 1650 mA/W at a bias voltage of 3 V. Also, the rise time of the dynamic response is determined to be about 87 ps, and the 3 dB bandwidth of the frequency response is obtained to be about 4 GHz.