High-responsivity and high-speed germanium photodetector for C + L application

Yiling Hu; Zhipeng Liu; Zhi Liu; Yupeng Zhu; Tao Men; Guangze Zhang; Jun Zheng; Yuhua Zuo; Buwen Cheng

doi:10.1088/1674-4926/25030017

J. Semicond. > 2025, Volume 46 > Issue 10 > 102401

ARTICLES

High-responsivity and high-speed germanium photodetector for C + L application

Yiling Hu^{1, 2, §}, Zhipeng Liu^{1, 2, §}, Zhi Liu^{1, 2,}, Yupeng Zhu^{1, 2}, Tao Men^{1, 2}, Guangze Zhang^{1, 2}, Jun Zheng^{1, 2}, Yuhua Zuo^{1, 2} and Buwen Cheng^{1, 2}

+ Author Affiliations

Corresponding author: Zhi Liu, zhiliu@semi.ac.cn

DOI: 10.1088/1674-4926/25030017CSTR: 32376.14.1674-4926.25030017

Abstract: A silicon-based germanium (Ge) photodetector working for C and L bands is proposed in this paper. The device features a novel asymmetric PIN structure, which contributes to a more optimized electric field distribution in Ge and a shorter effective width of depleted region. Meanwhile, the optical structure is designed carefully to enhance responsivity for broadband. Under −7 V, where the weak avalanche process happens, the responsivity of our device is 1.49 and 1.16 A/W at 1550 and 1600 nm, with bandwidth of 47.1 and 44.5 GHz, respectively. These performances demonstrate the significant application potential of the device in optical communication systems.

Key words: silicon photonics, germanium photodetector, asymmetric structure, DBR

References

[1]	Pons M, Valenzuela E, Rodríguez B, et al. Utilization of 5G technologies in IoT applications: Current limitations by interference and network optimization difficulties-a review. Sensors, 2023, 23(8), 3876 doi: 10.3390/s23083876
[2]	Keiser G E. A review of WDM technology and applications. Opt Fiber Technol, 1999, 5(1), 3 doi: 10.1006/ofte.1998.0275
[3]	Mukherjee B. WDM optical communication networks: Progress and challenges. IEEE J Sel Areas Commun, 2000, 18(10), 1810 doi: 10.1109/49.887904
[4]	Yoo S J B. Wavelength conversion technologies for WDM network applications. J Light Technol, 1996, 14(6), 955 doi: 10.1109/50.511595
[5]	Lopez V, Zhu B Y, Moniz D, et al. Optimized design and challenges for C&L band optical line systems. J Light Technol, 2020, 38(5), 1080 doi: 10.1109/JLT.2020.2968225
[6]	Steckler D, Lischke S, Kroh A, et al. Germanium photodiodes with 3-dB bandwidths >110 GHz and L-band responsivity of >0.7 A/W. IEEE Photonics Technol Lett, 2024, 36(12), 775 doi: 10.1109/LPT.2024.3398359
[7]	Cansizoglu H, Bartolo-Perez C, Gao Y, et al. Surface-illuminated photon-trapping high-speed Ge-on-Si photodiodes with improved efficiency up to 1700 nm. Photon Res, 2018, 6(7), 734 doi: 10.1364/PRJ.6.000734
[8]	Feng C H, Ying Z F, Zhao Z, et al. Wavelength-division-multiplexing (WDM)-based integrated electronic–photonic switching network (EPSN) for high-speed data processing and transportation. Nanophotonics, 2020, 9(15), 4579 doi: 10.1515/nanoph-2020-0356
[9]	Benedikovic D, Aubin G, Virot L, et al. High-speed silicon-germanium photodetectors for chip-scale photonic interconnects. 2021 Photonics North (PN), 2021, 1 doi: 10.1109/PN52152.2021.9597963
[10]	Yi L K, Liu D Q, Zhang P, et al. High performance waveguide integrated vertical silicon-based germanium avalanche photodetectors. Eighteenth National Conference on Laser Technology and Optoelectronics, 2023, 12792 doi: 10.1117/12.2689606
[11]	Fédéli J M, Virot L, Vivien L, et al. High-performance waveguide-integrated germanium PIN photodiodes for optical communication applications. 2014 7th International Silicon-Germanium Technology and Device Meeting (ISTDM), 2014, 131 doi: 10.1364/PRJ.1.000140
[12]	Wang H Q, Shi Y, Zuo Y, et al. High-performance waveguide coupled Germanium-on-silicon single-photon avalanche diode with independently controllable absorption and multiplication. Nanophotonics, 2023, 12(4), 705 doi: 10.1515/nanoph-2022-0663
[13]	Lozovoy K A, Douhan R M H, Dirko V V, et al. Silicon-based avalanche photodiodes: Advancements and applications in medical imaging. Nanomaterials, 2023, 13(23), 3078 doi: 10.3390/nano13233078
[14]	Hu Y L, Liu Z, Zhu Y P, et al. High-speed waveguide lateral Ge/Si avalanche photodetector for C-band and L-band. Opt Express, 2024, 32(15), 25598 doi: 10.1364/OE.522133
[15]	Lin Y D, Ma D H, Hong Lee K, et al. PIC-integrable, uniformly tensile-strained Ge-on-insulator photodiodes enabled by recessed SiNx stressor. Photon Res, 2021, 9(7), 1255 doi: 10.1364/PRJ.419776
[16]	Liow T Y, Lim A E, Duan N, et al. Waveguide germanium photodetector with high bandwidth and high L-band responsivity. Optical Fiber Communication Conference/National Fiber Optic Engineers Conference 2013, 2013, OM3K.2
[17]	Lischke S, Knoll D, Mai C, et al. High-bandwidth, waveguide-coupled Ge p-i-n photodiode with high C- and L-band responsivity. 2015 IEEE 12th International Conference on Group IV Photonics (GFP), 2015, 17 doi: 10.1109/Group4.2015.7305932

Fig. 1. (Color online) (a) The three-dimensional schematic (Ⅰ) and cross-section (Ⅱ) view of the device structure. (b) The simulated static optical field distribution. (c) The simulated electric field at −7 V.

DownLoad: Full-Size Img PowerPoint

Fig. 2. (Color online) The measured I−V curves of the proposed device at (a)1530 nm, (b)1550 nm, (c)1580 nm, and (d)1600 nm with the changing optical power.

DownLoad: Full-Size Img PowerPoint

Fig. 3. (Color online) (a) The measured C−V curves of the device. (b) The responsivity spectrum of the device under −3, −5, and −7 V across the entire C and L band (from 1530 to 1625 nm) when the input optical power is set to −15.7 dBm.

DownLoad: Full-Size Img PowerPoint

Fig. 4. (Color online) Experimental setup for (a) small-signal radio frequency (RF) measurements and (b) eye diagram measurements. The gray and black lines represent the electrical and optical links, respectively (VNA, vector network analyzer; PC, polarization controller; LN MZM, lithium niobate Mach−Zehnder modulator; VOA, variable optical attenuator; DUT, device under test).

DownLoad: Full-Size Img PowerPoint

Fig. 5. (Color online) Normalized optic-electro frequency response (S₂₁) of the Ge PD at (a)1530 nm, (b)1550 nm, (c)1580 nm, and (d)1600 nm under the bias voltages of −2 to −9 V.

DownLoad: Full-Size Img PowerPoint

Fig. 6. (Color online) 3-dB bandwidths and responsivity at 1550 and 1600 nm from −2 to −8 V.

DownLoad: Full-Size Img PowerPoint

Fig. 7. (Color online) (a) An equivalent circuit model for Ge-PD. (b) Measured and simulated reflection coefficients for Ge-PD at −4 V.

DownLoad: Full-Size Img PowerPoint

Fig. 8. (Color online) (a) Measured 56 and 70 Gbps NRZ eye diagrams under 5 and 7 V at 1550 nm wavelength. (b) Measured 56 and 70 Gbps NRZ eye diagrams under 5 and 7 V at 1600 nm wavelength.

DownLoad: Full-Size Img PowerPoint

Table 1. Extracted parameters for Ge-PD at −4 V.

Parameter	Value
R_s	8 Ω
R_Si	8000 Ω
C_para	13.5 fF
R_para	0.05 Ω
C_j	25 fF
C_ox	180 fF
L_para	40 pH

DownLoad: CSV

Table 2. Summary of the reported C and L band PDs.

Ref.	Wavelength (nm)	Responsivity (A/W)	Bandwidth (GHz)	Dark current
[15]	1500−1630	1	3	41.7 μA
[16]	1524.9−1611.5	1.3@ −8.8 V	27	1.29 μA
[17]	1625	0.8	40	100 nA
[6]	1620	0.7	110	500 nA
This work	1530−1630	1.49@1550 nm 1.16@1600 nm	47.1@1550 nm 44.5@1600 nm	10 nA@−3 V 4.7 μA@−7 V

DownLoad: CSV

[1]	Pons M, Valenzuela E, Rodríguez B, et al. Utilization of 5G technologies in IoT applications: Current limitations by interference and network optimization difficulties-a review. Sensors, 2023, 23(8), 3876 doi: 10.3390/s23083876
[2]	Keiser G E. A review of WDM technology and applications. Opt Fiber Technol, 1999, 5(1), 3 doi: 10.1006/ofte.1998.0275
[3]	Mukherjee B. WDM optical communication networks: Progress and challenges. IEEE J Sel Areas Commun, 2000, 18(10), 1810 doi: 10.1109/49.887904
[4]	Yoo S J B. Wavelength conversion technologies for WDM network applications. J Light Technol, 1996, 14(6), 955 doi: 10.1109/50.511595
[5]	Lopez V, Zhu B Y, Moniz D, et al. Optimized design and challenges for C&L band optical line systems. J Light Technol, 2020, 38(5), 1080 doi: 10.1109/JLT.2020.2968225
[6]	Steckler D, Lischke S, Kroh A, et al. Germanium photodiodes with 3-dB bandwidths >110 GHz and L-band responsivity of >0.7 A/W. IEEE Photonics Technol Lett, 2024, 36(12), 775 doi: 10.1109/LPT.2024.3398359
[7]	Cansizoglu H, Bartolo-Perez C, Gao Y, et al. Surface-illuminated photon-trapping high-speed Ge-on-Si photodiodes with improved efficiency up to 1700 nm. Photon Res, 2018, 6(7), 734 doi: 10.1364/PRJ.6.000734
[8]	Feng C H, Ying Z F, Zhao Z, et al. Wavelength-division-multiplexing (WDM)-based integrated electronic–photonic switching network (EPSN) for high-speed data processing and transportation. Nanophotonics, 2020, 9(15), 4579 doi: 10.1515/nanoph-2020-0356
[9]	Benedikovic D, Aubin G, Virot L, et al. High-speed silicon-germanium photodetectors for chip-scale photonic interconnects. 2021 Photonics North (PN), 2021, 1 doi: 10.1109/PN52152.2021.9597963
[10]	Yi L K, Liu D Q, Zhang P, et al. High performance waveguide integrated vertical silicon-based germanium avalanche photodetectors. Eighteenth National Conference on Laser Technology and Optoelectronics, 2023, 12792 doi: 10.1117/12.2689606
[11]	Fédéli J M, Virot L, Vivien L, et al. High-performance waveguide-integrated germanium PIN photodiodes for optical communication applications. 2014 7th International Silicon-Germanium Technology and Device Meeting (ISTDM), 2014, 131 doi: 10.1364/PRJ.1.000140
[12]	Wang H Q, Shi Y, Zuo Y, et al. High-performance waveguide coupled Germanium-on-silicon single-photon avalanche diode with independently controllable absorption and multiplication. Nanophotonics, 2023, 12(4), 705 doi: 10.1515/nanoph-2022-0663
[13]	Lozovoy K A, Douhan R M H, Dirko V V, et al. Silicon-based avalanche photodiodes: Advancements and applications in medical imaging. Nanomaterials, 2023, 13(23), 3078 doi: 10.3390/nano13233078
[14]	Hu Y L, Liu Z, Zhu Y P, et al. High-speed waveguide lateral Ge/Si avalanche photodetector for C-band and L-band. Opt Express, 2024, 32(15), 25598 doi: 10.1364/OE.522133
[15]	Lin Y D, Ma D H, Hong Lee K, et al. PIC-integrable, uniformly tensile-strained Ge-on-insulator photodiodes enabled by recessed SiNx stressor. Photon Res, 2021, 9(7), 1255 doi: 10.1364/PRJ.419776
[16]	Liow T Y, Lim A E, Duan N, et al. Waveguide germanium photodetector with high bandwidth and high L-band responsivity. Optical Fiber Communication Conference/National Fiber Optic Engineers Conference 2013, 2013, OM3K.2
[17]	Lischke S, Knoll D, Mai C, et al. High-bandwidth, waveguide-coupled Ge p-i-n photodiode with high C- and L-band responsivity. 2015 IEEE 12th International Conference on Group IV Photonics (GFP), 2015, 17 doi: 10.1109/Group4.2015.7305932

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Received: 11 March 2025 Revised: 29 April 2025 Online: Accepted Manuscript: 14 May 2025Uncorrected proof: 19 May 2025Published: 09 October 2025

Article Navigation > Journal of Semiconductors > 2025 > 46(10): 102401

Yiling Hu, Zhipeng Liu, Zhi Liu, Yupeng Zhu, Tao Men, Guangze Zhang, Jun Zheng, Yuhua Zuo, Buwen Cheng. High-responsivity and high-speed germanium photodetector for C + L application[J]. Journal of Semiconductors, 2025, 46(10): 102401. doi: 10.1088/1674-4926/25030017 ****Y L Hu, Z P Liu, Z Liu, Y P Zhu, T Men, G Z Zhang, J Zheng, Y H Zuo, and B W Cheng, High-responsivity and high-speed germanium photodetector for C + L application[J]. J. Semicond., 2025, 46(10), 102401 doi: 10.1088/1674-4926/25030017

Citation:

Y L Hu, Z P Liu, Z Liu, Y P Zhu, T Men, G Z Zhang, J Zheng, Y H Zuo, and B W Cheng, High-responsivity and high-speed germanium photodetector for C + L application[J]. J. Semicond., 2025, 46(10), 102401 doi: 10.1088/1674-4926/25030017

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High-responsivity and high-speed germanium photodetector for C + L application

DOI: 10.1088/1674-4926/25030017

CSTR: 32376.14.1674-4926.25030017

Yiling Hu^{1, 2, §},
Zhipeng Liu^{1, 2, §},
Zhi Liu^{1, 2,},
Yupeng Zhu^{1, 2},
Tao Men^{1, 2},
Guangze Zhang^{1, 2},
Jun Zheng^{1, 2},
Yuhua Zuo^{1, 2},
Buwen Cheng^{1, 2}

1.
State Key Laboratory of Optoelectronic Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
2.
College of Materials Science and Opto-electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China

More Information

Yiling Hu received the B.S. degree from Nankai University, Tianjin, China, in 2022. Now she is working toward the Ph.D. degree at the Institute of Semiconductors, Chinese Academy of Sciences, Beijing, China. Her research interests include high-speed silicon-based photodetectors and avalanche photodiodes
Zhipeng Liu received the B.S. degree from the University of Chinese Academy of Sciences, Beijing, China, in 2022. He is currently working toward the Ph.D. degree at the Institute of Semiconductors, Chinese Academy of Sciences, Beijing, China. His research interests include high-speed silicon-based photodetectors
Zhi Liu received the Ph.D. degree from Institute of Semiconductors, Chinese Academy of Sciences, in 2014. Since 2014, he has been with the Institute of Semiconductors, Chinese Academy of Sciences. His research interests include silicon-based group Ⅳ material growth and silicon photonics
Corresponding author: zhiliu@semi.ac.cn
Received Date: 2025-03-11
Revised Date: 2025-04-29

Available Online: 2025-05-14

Abstract

Abstract

A silicon-based germanium (Ge) photodetector working for C and L bands is proposed in this paper. The device features a novel asymmetric PIN structure, which contributes to a more optimized electric field distribution in Ge and a shorter effective width of depleted region. Meanwhile, the optical structure is designed carefully to enhance responsivity for broadband. Under −7 V, where the weak avalanche process happens, the responsivity of our device is 1.49 and 1.16 A/W at 1550 and 1600 nm, with bandwidth of 47.1 and 44.5 GHz, respectively. These performances demonstrate the significant application potential of the device in optical communication systems.
- silicon photonics,
- germanium photodetector,
- asymmetric structure,
- DBR

^§Yiling Hu and Zhipeng Liu contributed equally to this work and should be considered as co-first authors.

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References(17)