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Low-Voltage High-Speed (18 GHz/1 V) Evanescent-Coupled Thin-Film-Ge Lateral PIN Photodetectors Integrated on Si Waveguide

2008; Institute of Electrical and Electronics Engineers; Volume: 20; Issue: 17 Linguagem: Inglês

10.1109/lpt.2008.928087

1941-0174

J. Wang, W.Y. Loh, K.T. Chua, H. Zang, Yujie Xiong, Shuyin Tan, Mingbin Yu, S.J. Lee, G. Q. Lo, Dim‐Lee Kwong,

Semiconductor Quantum Structures and Devices

This letter presents the device performance of scaled thin-film-Ge lateral PIN photodetectors integrated on a Si waveguide. The photodetectors are with closely spaced p + /n + regions (0.8 mum) on a Ge region with short length (5-20 mum) and narrow width (2.4 mum). Though with a thin Ge layer (~220 nm including bottom SiGe buffer), light is evanescent-coupled from the Si waveguide effectively to the overlying Ge detector. The device exhibits f 3 dB bandwidth of 18 GHz with external responsivity of 0.13 A/W for 1550 nm at -1 V. Considering the coupling loss and waveguide loss, the internal responsivity is as high as 0.65 A/W. It is shown that with increasing detector length, the devices' internal quantum efficiency can be improved to ~90% and by suppressing parasitic effects, speed can be boosted further towards several tens of gigahertz.