Photonics Research, Volume. 12, Issue 12, 2931(2024)

Low dark current and low voltage germanium avalanche photodetector for a silicon photonic link

Xuetong Li1, Huan Qu1, Xiaobin Liu2, Qijie Xie2,4, Weipeng Wang1, Yingzhi Li1, Baisong Chen1, Heming Hu1, Jie Li1, Zihao Zhi1, Patrick Lo3, Quanxin Na2, Xueyan Li1, Lei Wang2, Xiaolong Hu1,5, and Junfeng Song1,2、*
Author Affiliations
  • 1State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
  • 2Peng Cheng Laboratory, Shenzhen 518000, China
  • 3Advance Micro Foundry Pte Ltd., Singapore 117685, Singapore
  • 4e-mail: xieqj@pcl.ac.cn
  • 5e-mail: huxiaolong@jlu.edu.cn
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    Figures & Tables(10)
    (a) Schematic diagram for cross section of the Ge APD. (b) Simulated results for electric field distribution in the cross section of the Ge APD when the bias voltage is −8 V.
    Schematic diagram for the proposed waveguide Ge APD.
    (a) Plots for the photocurrent against the bias voltage in the cases of 1550 nm incident light with optical power varied from −25 dBm to 0 dBm. The measured dark current with the bias voltage severs as a reference. (b) Simulated results for the distributed electric field along the z-direction in Ge under the voltages of 0 V, −2 V,−4 V,−6 V,−7 V,−8 V, and −8.5 V.
    (a) Plots of the measured responsivity versus bias voltage under the input optical power varied from −25 dBm to 0 dBm. (b) Responsivity versus optical power at the bias voltage of −2 V and −8 V. (c) Photocurrent versus optical power at the bias voltage of −2 V and −8 V.
    (a) Measured results for RF response of the Ge APD under the bias voltage varied from 0 V to −11 V in the case of incident optical power of −17 dBm. The result is normalized. (b) Simulated results for electric field along the x-direction in silicon at the voltage of 0,−2,−4,−6,−7,−8, and −8.5V.
    (a) Equivalent circuit of the APD. Measured and simulated RF response of APD at a bias voltage of (b) −5 V and (c) −11 V.
    Experimental setup for characterizing the present APD eye diagram test. The red lines represent the optical connections, and the blue lines represent the electric connections. MZM, Mach–Zehnder modulator; DC, direct current; AWG, arbitrary waveform generator; PC, polarization controller; OSC, oscilloscope.
    Electrical eye diagrams of 20 Gbps, 25 Gbps, and 32 Gbps NRZ signals with −11 dBm optical power at the bias voltage of −11 V and −12 V.
    • Table 1. Fitted Electric Circuit Parameters of Ge/Si APD under the Bias Voltage of −5 V and −11 V

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      Table 1. Fitted Electric Circuit Parameters of Ge/Si APD under the Bias Voltage of −5 V and −11 V

      ParameterValue
      5  V11  V
      Rl  (kΩ)0.56.3
      Ca  (fF)121563.79
      Ra  (Ω)87370
      La  (nH)230722.8
      Rs  (Ω)6053.81
      Cp  (fF)9.59.25
      Rp  (Ω)8.78.7
      Lp  (nH)2.22
    • Table 2. Summary of the Reported Ge/Si APDs and Ge APDs

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      Table 2. Summary of the Reported Ge/Si APDs and Ge APDs

      Ref.Device TypeRequirement for Silicon Epitaxy (Yes or No)Avalanche Region (Si or Ge)Dark Current Density (A/μm2)λ (nm)Primary Responsivity (A/W)Avalanche Voltage (V)3 dB BW (GHz)
      [30]SurfaceNoSi1.7×101215500.22−2511.5
      [15]WaveguideYesSi1×101215501.05−1025
      [16]WaveguideYesSi/15500.48−6.418.9
      [31]WaveguideNoSi1.4×101013100.64−1227
      [32]WaveguideNoSi3.3×101013100.96−1527
      [17]WaveguideNoGe2×101015500.4−711
      [18]WaveguideNoGe/13100.3−515.2
      [19]WaveguideNoGe5.3×101015500.8−8.0431
      This workWaveguideNoGe6.1×101115501.1−8.425
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    Xuetong Li, Huan Qu, Xiaobin Liu, Qijie Xie, Weipeng Wang, Yingzhi Li, Baisong Chen, Heming Hu, Jie Li, Zihao Zhi, Patrick Lo, Quanxin Na, Xueyan Li, Lei Wang, Xiaolong Hu, Junfeng Song, "Low dark current and low voltage germanium avalanche photodetector for a silicon photonic link," Photonics Res. 12, 2931 (2024)

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    Paper Information

    Category: Silicon Photonics

    Received: Jul. 2, 2024

    Accepted: Oct. 4, 2024

    Published Online: Nov. 29, 2024

    The Author Email: Junfeng Song (songjf@jlu.edu.cn)

    DOI:10.1364/PRJ.534507

    CSTR:32188.14.PRJ.534507

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