High-speed and low dark current silicon-waveguide-coupled III-V photodetectors selectively grown on SOI
Ying Xue, Yu Han, Yi Wang, Jie Li, Jingyi Wang, Zunyue Zhang, Xinlun Cai, Hon Ki Tsang, Kei May Lau
Abstract
Seamlessly integrating III-V active devices with Si passive components in a monolithic manner is the key for fully integrated Si photonics. In this article, we demonstrate high-performance III-V photodetectors directly grown on industry-standard (001)-oriented silicon-on-insulator (SOI) wafers and intimately coupled with Si waveguides. The Si-waveguide-coupled III-V photodetectors feature a low dark current of 60 pA corresponding to a current density of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>0.002</mml:mn> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">A</mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> <mml:mi mathvariant="normal">c</mml:mi> </mml:mrow> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> </mml:mrow> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:math> , a large photocurrent exceeding 1 mA, responsivities of 0.4 A/W at 1.3 µm and 0.2 A/W at 1.5 µm, and a large detection wavelength range over the entire telecom band. High-speed measurements reveal a 3 dB bandwidth over 52 GHz and a data communication rate of 112 Gb/s with four-level pulse-amplitude modulation and 100 Gb/s with on–off keying. The monolithic integration scheme demonstrated for III-V photodetectors in this work is also applicable to future seamless integration of III-V lasers on the Si-photonics platform.