Plasmon-enhanced graphene photodetector with CMOS-compatible titaniumnitride
Mohammed Alaloul, Mahmoud Rasras
Abstract
Graphene has emerged as an ultrafast optoelectronic material for on-chip photodetector applications. The 2D nature of graphene enables its facile integration with complementary metal–oxide semiconductor (CMOS) microelectronics and silicon photonics, yet graphene absorbs only <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>∼</mml:mo> </mml:mrow> <mml:mn>2.3</mml:mn> <mml:mi mathvariant="normal">%</mml:mi> </mml:math> of light. Plasmonic metals can enhance the responsivity of graphene photodetectors, but may result in CMOS-incompatible devices, depending on the choice of metal. Here we propose a plasmon-enhanced photothermoelectric graphene detector using CMOS-compatible titanium nitride on the silicon-on-insulator platform. The device performance is quantified by its responsivity, operation speed, and noise equivalent power. Its bandwidth exceeds 100 GHz, and it exhibits a nearly flat photoresponse across the telecom C-band. The photodetector responsivity is as high as 1.4 A/W (1.1 A/W external) at an ultra-compact length of 3.5 µm, which is the most compact footprint reported for a graphene-based waveguide photodetector. Furthermore, it operates at zero-bias, consumes zero energy, and has an ultra-low intrinsic noise equivalent power ( <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">N</mml:mi> <mml:mi mathvariant="normal">E</mml:mi> <mml:mi mathvariant="normal">P</mml:mi> </mml:mrow> </mml:mrow> <mml:mo><</mml:mo> <mml:mn>20</mml:mn> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">p</mml:mi> <mml:mi mathvariant="normal">W</mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> </mml:mrow> </mml:mrow> <mml:msqrt> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">H</mml:mi> <mml:mi mathvariant="normal">z</mml:mi> </mml:mrow> </mml:mrow> </mml:msqrt> </mml:math> ).