## Design of broadband and high-output power uni-traveling-carrier photodiodes |

Optics Express, Vol. 21, Issue 6, pp. 6943-6954 (2013)

http://dx.doi.org/10.1364/OE.21.006943

Acrobat PDF (4418 KB)

### Abstract

In this paper, physically-based simulations are carried out to investigate and design broadband and high-output power uni-traveling carrier (UTC) photodiodes. The physical model is first verified by comparison to experimentally measured results. The graded-bandgap structure, which can induce potential gradient, is considered to be used in the absorption layers. It is shown that the electric field in the absorption layer is increased by the gradient, thus the performance of bandwidth and saturation current is improved by 36.6% and 40% respectively for our considered photodiode. Moreover, a modified graded-bandgap structure is proposed to further increase the electric field, and an additional 9.5% improvement in bandwidth is achieved. The final proposed UTC-PD structures will result in 399-GHz bandwidth and 49-mA DC saturation current.

© 2013 OSA

## 1. Introduction

12. J.-W. Shi, F.-M. Kuo, and J. E. Bowers, “Design and analysis of ultra-high-speed near-ballistic uni-traveling-carrier photodiodes under a 50-Ω load for high-power performance,” IEEE Photon. Technol. Lett. **24**(7), 533–535 (2012). [CrossRef]

20. Y.-S. Wu, J.-W. Shi, and P.-H. Chiu, “Analytical modeling of a high-performance near-ballistic uni-traveling-carrier photodiode at a 1.55-μm wavelength,” IEEE Photon. Technol. Lett. **18**(8), 938–940 (2006). [CrossRef]

11. Z. Li, H. Pan, H. Chen, A. Beling, and J. C. Campbell, “High-saturation-current modified uni-traveling-carrier photodiode with cliff layer,” IEEE J. Quantum Electron. **46**(5), 626–632 (2010). [CrossRef]

12. J.-W. Shi, F.-M. Kuo, and J. E. Bowers, “Design and analysis of ultra-high-speed near-ballistic uni-traveling-carrier photodiodes under a 50-Ω load for high-power performance,” IEEE Photon. Technol. Lett. **24**(7), 533–535 (2012). [CrossRef]

## 2. Physical modeling

### 2.1 Simulator

### 2.2 Simulation of UTC-PDs

11. Z. Li, H. Pan, H. Chen, A. Beling, and J. C. Campbell, “High-saturation-current modified uni-traveling-carrier photodiode with cliff layer,” IEEE J. Quantum Electron. **46**(5), 626–632 (2010). [CrossRef]

12. J.-W. Shi, F.-M. Kuo, and J. E. Bowers, “Design and analysis of ultra-high-speed near-ballistic uni-traveling-carrier photodiodes under a 50-Ω load for high-power performance,” IEEE Photon. Technol. Lett. **24**(7), 533–535 (2012). [CrossRef]

11. Z. Li, H. Pan, H. Chen, A. Beling, and J. C. Campbell, “High-saturation-current modified uni-traveling-carrier photodiode with cliff layer,” IEEE J. Quantum Electron. **46**(5), 626–632 (2010). [CrossRef]

**24**(7), 533–535 (2012). [CrossRef]

4. H. Ito, S. Kodama, Y. Muramoto, T. Furuta, T. Nagatsuma, and T. Ishibashi, “High-speed and high-output InP–InGaAs unitraveling-carrier photodiodes,” IEEE J. Sel. Top. Quantum Electron. **10**(4), 709–727 (2004). [CrossRef]

^{2}. It is clearly obvious that higher hole charge density indeed improves the bandwidth. Consequently, the physically-based simulations are reliable. It should be mentioned that although in the simulation, parasitic elements in actual circuits are not included, and the series resistance is used to fit the simulated bandwidth with measured data, the physical effects showing bandwidth changed with device active area, external bias voltage, and illumination power are successfully predicted. All the fitted parameters are kept in the following simulations to ensure that the modeling is taken under the same condition.

## 3. Device design and analysis

### 3.1 Graded bandgap design

19. J.-W. Shi, F.-M. Kuo, C.-J. Wu, C. L. Chang, C.-Y. Liu, C. Y. Chen, and J.-I. Chyi, “Extremely high saturation current-bandwidth product performance of a near-ballistic uni-traveling-carrier photodiode with a flip-chip bonding structure,” IEEE J. Quantum Electron. **46**(1), 80–86 (2010). [CrossRef]

_{1-x}Ga

_{x}As

_{y}P

_{1-y}or In

_{1-x-y}Al

_{x}Ga

_{y}As with lattice matched to InP can provide a range of bandgaps, which can be used to construct a continuous compositionally-graded bandgap structure. Here, the graded absorption layer using In

_{1-x}Ga

_{x}As

_{y}P

_{1-y}will be considered.

_{1-x}Ga

_{x}As

_{y}P

_{1-y}absorption layer, two basic conditions should be satisfied.

- 2) To excite the interband transition by the light around 1.5-μm wavelength,
*E*should be no more than 0.82 eV._{g}

*x*from 0.38 to 0.47, and correspondingly, the range of

*y*is from 0.82 to 1. Therefore, the maximum potential difference is formed between In

_{0.62}Ga

_{0.38}As

_{0.82}P

_{0.18}and In

_{0.53}Ga

_{0.47}As.

_{0.62}Ga

_{0.38}As

_{0.82}P

_{0.18}→In

_{0.53}Ga

_{0.47}As is considered to substitute for the In

_{0.53}Ga

_{0.47}As absorption layer of PA (0.9-μm undepleted part) and PB. Note that the graded InAlGaAs transition layer is also replaced with InGaAsP in PB structure. For clarity, the layer parameters of PA and PB with the graded bandgap absorption layers are also listed in Tables 1 and 2, respectively. If the top of the P contact layer is set as the origin of the depth (

*d*), the relations between the composition fraction

*x*and

*d*(in μm) are

*y*is calculated according to condition 1, i.e. (2). The electric field distributions and the band diagram in the 0.15-μm-thickness absorption layer (from 0.12 to 0.27 μm) of PB are plotted in Fig. 3 . It is seen that the built-in electric filed induced by the graded doping is greater than ~2 kV/cm as mentioned above [19

19. J.-W. Shi, F.-M. Kuo, C.-J. Wu, C. L. Chang, C.-Y. Liu, C. Y. Chen, and J.-I. Chyi, “Extremely high saturation current-bandwidth product performance of a near-ballistic uni-traveling-carrier photodiode with a flip-chip bonding structure,” IEEE J. Quantum Electron. **46**(1), 80–86 (2010). [CrossRef]

### 3.2 Modified graded bandgap design

**24**(7), 533–535 (2012). [CrossRef]

19. J.-W. Shi, F.-M. Kuo, C.-J. Wu, C. L. Chang, C.-Y. Liu, C. Y. Chen, and J.-I. Chyi, “Extremely high saturation current-bandwidth product performance of a near-ballistic uni-traveling-carrier photodiode with a flip-chip bonding structure,” IEEE J. Quantum Electron. **46**(1), 80–86 (2010). [CrossRef]

**24**(7), 533–535 (2012). [CrossRef]

^{2}to 14 μm

^{2}, the RC bandwidth can reach 380 GHz. Therefore, it is highly possible that improving the electron transit speed in the absorption layer by using graded bandgap is still an effective way to increase the bandwidth for many designs of broadband photodiodes.

### 3.3 Saturation current

*κ*) of the refractive index to evaluate the optic-to-electric (O-E) conversion efficiency, in the simulations

*κ*is determined by fitting the responsivity (the slopes of the curves in Fig. 7 ) to the measured result in [12

**24**(7), 533–535 (2012). [CrossRef]

*κ*is assumed the same for In

_{0.53}Ga

_{0.47}As and InGaAsP. Both InGaAsP (low P fraction for our structure) and In

_{0.53}Ga

_{0.47}As are direct bandgap materials and have similar band structures, therefore, this approximation is acceptable and may not lead to significant error in O-E conversion efficiency of InGaAsP. As shown in Fig. 7, the DC current increases linearly with the increasing light power till the inflection point, and then the current becomes to saturate. The reduction of the slope indicates a decreased responsivity due to the space charge effect from the carrier storage at high-optical input [4

4. H. Ito, S. Kodama, Y. Muramoto, T. Furuta, T. Nagatsuma, and T. Ishibashi, “High-speed and high-output InP–InGaAs unitraveling-carrier photodiodes,” IEEE J. Sel. Top. Quantum Electron. **10**(4), 709–727 (2004). [CrossRef]

**46**(5), 626–632 (2010). [CrossRef]

**46**(5), 626–632 (2010). [CrossRef]

**46**(5), 626–632 (2010). [CrossRef]

### 3.4 Fabrication considerations

_{1-x}Ga

_{x}As

_{y}P

_{1-y}and In

_{1-x-y}Al

_{x}Ga

_{y}As can be grown by epitaxy techniques, such as MBE, MOVPE, or MOCVD, etc. For In

_{1-x}Ga

_{x}As

_{y}P

_{1-y}grown by MOCVD, the quality of linearly grading can be ensured except for large composition ranges, which can meet the requirement of the graded absorption layer. While for the thin transition layer with a large grading range from In

_{0.53}Ga

_{0.47}As to InP, an alternative method is using step grading. The differences in simulated performances between the linearly continuous grading and a 3-step grading in transition layer are negligible. In addition, In

_{1-x-y}Al

_{x}Ga

_{y}As is easier to control in MBE. Therefore, the use of In

_{1-x-y}Al

_{x}Ga

_{y}As graded layer may be more practical and economical. The design method of a continuous compositionally-graded In

_{1-x-y}Al

_{x}Ga

_{y}As absorption layer is similar to that of In

_{1-x}Ga

_{x}As

_{y}P

_{1-y}.

## 4. Conclusion

**24**(7), 533–535 (2012). [CrossRef]

## Acknowledgment

## References and links

1. | C. Cox, E. Ackerman, G. Betts, and J. Prince, “Limits on the performance of RF-over-fiber links and their impact on device design,” IEEE Trans. Microw. Theory Tech. |

2. | J.-W. Shi, C.-B. Huang, and C.-L. Pan, “Millimeter-wave photonic wireless links for very high data rate communication,” NPG Asia Mater. |

3. | M. Achouche, G. Glastre, C. Caillaud, M. Lahrichi, M. Chtioui, and D. Carpentier, “InGaAs communication photodiodes: from low- to high-power-level designs,” IEEE Photonics J. |

4. | H. Ito, S. Kodama, Y. Muramoto, T. Furuta, T. Nagatsuma, and T. Ishibashi, “High-speed and high-output InP–InGaAs unitraveling-carrier photodiodes,” IEEE J. Sel. Top. Quantum Electron. |

5. | T. Ishibashi, N. Shimizu, S. Kodama, H. Ito, T. Nagatsuma, and T. Furuta, “Uni-traveling-carrier photodiodes,” in |

6. | T. Ishibashi, S. Kodoma, N. Shimizu, and T. Furuta, “High-speed response of uni-traveling-carrier photodiodes,” Jpn. J. Appl. Phys. |

7. | M. Chtioui, A. Enard, D. Carpentier, S. Bernard, B. Rousseau, F. Lelarge, F. Pommereau, and M. Achouche, “High-performance uni-traveling-carrier photodiodes with a new collector design,” IEEE Photon. Technol. Lett. |

8. | D.-H. Jun, J.-H. Jang, I. Adesida, and J.-I. Song, “Improved efficiency bandwidth product of modified uni-traveling carrier photodiode structures using an undoped photo-absorption layer,” Jpn. J. Appl. Phys. |

9. | X. Wang, N. Duan, H. Chen, and J. C. Campbell, “InGaAs-InP photodiodes with high responsivity and high saturation power,” IEEE Photon. Technol. Lett. |

10. | M. Chtioui, F. Lelarge, A. Enard, F. Pommereau, D. Carpentier, A. Marceaux, F. van Dijk, and M. Achouche, “High responsivity and high power UTC and MUTC GaInAs-InP photodiodes,” IEEE Photon. Technol. Lett. |

11. | Z. Li, H. Pan, H. Chen, A. Beling, and J. C. Campbell, “High-saturation-current modified uni-traveling-carrier photodiode with cliff layer,” IEEE J. Quantum Electron. |

12. | J.-W. Shi, F.-M. Kuo, and J. E. Bowers, “Design and analysis of ultra-high-speed near-ballistic uni-traveling-carrier photodiodes under a 50-Ω load for high-power performance,” IEEE Photon. Technol. Lett. |

13. | J.-W. Shi, Y.-S. Wu, C.-Y. Wu, P.-H. Chiu, and C.-C. Hong, “High-speed, high-responsivity, and high-power performance of near-ballistic uni-traveling-carrier photodiode at 1.55-μm wavelength,” IEEE Photon. Technol. Lett. |

14. | M. Chtioui, A. Enard, D. Carpentier, S. Bernard, B. Rousseau, F. Lelarge, F. Pommereau, and M. Achouche, “High-power and high-linearity uni-traveling-carrier photodiodes for analog photonic links,” IEEE Photon. Technol. Lett. |

15. | H. Fukano, Y. Muramoto, K. Takahata, and Y. Matsuoka, “High efficiency edge-illuminated unitravelling-carrier-structure refracting-facet photodiode,” Electron. Lett. |

16. | S. Demiguel, N. Li, X. Li, X. Zheng, J. Kim, J. C. Campbell, H. Lu, and A. Anselm, “Very high-responsivity evanescently coupled photodiodes integrating a short planar multimode waveguide for high-speed applications,” IEEE Photon. Technol. Lett. |

17. | J. Klamkin, S. M. Madison, D. C. Oakley, A. Napoleone, F. J. O’Donnell, M. Sheehan, L. J. Missaggia, J. M. Caissie, J. J. Plant, and P. W. Juodawlkis, “Uni-traveling-carrier variable confinement waveguide photodiodes,” Opt. Express |

18. | M. Hosseinifar, V. Ahmadi, and G. Abaeiani, “Microring-based unitraveling carrier photodiodes for high bandwidth-efficiency product photodetection in optical communication,” J. Lightwave Technol. |

19. | J.-W. Shi, F.-M. Kuo, C.-J. Wu, C. L. Chang, C.-Y. Liu, C. Y. Chen, and J.-I. Chyi, “Extremely high saturation current-bandwidth product performance of a near-ballistic uni-traveling-carrier photodiode with a flip-chip bonding structure,” IEEE J. Quantum Electron. |

20. | Y.-S. Wu, J.-W. Shi, and P.-H. Chiu, “Analytical modeling of a high-performance near-ballistic uni-traveling-carrier photodiode at a 1.55-μm wavelength,” IEEE Photon. Technol. Lett. |

21. | R. Stratton, “Diffusion of hot and cold electrons in semiconductor barriers,” Phys. Rev. |

22. | R. Stratton, “Semiconductor current-flow equations (diffusion and degeneracy),” IEEE Trans. Electron. Dev. |

23. | New semiconductor materials, characteristics and properties, http://www.ioffe.rssi.ru/SVA/NSM/. |

24. | S. Adachi, |

**OCIS Codes**

(060.2330) Fiber optics and optical communications : Fiber optics communications

(230.5170) Optical devices : Photodiodes

(250.0040) Optoelectronics : Detectors

**ToC Category:**

Fiber Optics and Optical Communications

**History**

Original Manuscript: January 28, 2013

Revised Manuscript: March 4, 2013

Manuscript Accepted: March 5, 2013

Published: March 13, 2013

**Citation**

Rong Zhang, Bouchaib Hraimel, Xue Li, Peng Zhang, and Xiupu Zhang, "Design of broadband and high-output power uni-traveling-carrier photodiodes," Opt. Express **21**, 6943-6954 (2013)

http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-6-6943

Sort: Year | Journal | Reset

### References

- C. Cox, E. Ackerman, G. Betts, and J. Prince, “Limits on the performance of RF-over-fiber links and their impact on device design,” IEEE Trans. Microw. Theory Tech.54(2), 906–920 (2006). [CrossRef]
- J.-W. Shi, C.-B. Huang, and C.-L. Pan, “Millimeter-wave photonic wireless links for very high data rate communication,” NPG Asia Mater.3(4), 41–48 (2011). [CrossRef]
- M. Achouche, G. Glastre, C. Caillaud, M. Lahrichi, M. Chtioui, and D. Carpentier, “InGaAs communication photodiodes: from low- to high-power-level designs,” IEEE Photonics J.2(3), 460–468 (2010). [CrossRef]
- H. Ito, S. Kodama, Y. Muramoto, T. Furuta, T. Nagatsuma, and T. Ishibashi, “High-speed and high-output InP–InGaAs unitraveling-carrier photodiodes,” IEEE J. Sel. Top. Quantum Electron.10(4), 709–727 (2004). [CrossRef]
- T. Ishibashi, N. Shimizu, S. Kodama, H. Ito, T. Nagatsuma, and T. Furuta, “Uni-traveling-carrier photodiodes,” in Ultrafast Electronics Optoelectronics OSA Spring Topical Meeting, Technical Digest (Optical Society of America, 1997), pp. 166–168.
- T. Ishibashi, S. Kodoma, N. Shimizu, and T. Furuta, “High-speed response of uni-traveling-carrier photodiodes,” Jpn. J. Appl. Phys.36(Part 1, No. 10), 6263–6268 (1997). [CrossRef]
- M. Chtioui, A. Enard, D. Carpentier, S. Bernard, B. Rousseau, F. Lelarge, F. Pommereau, and M. Achouche, “High-performance uni-traveling-carrier photodiodes with a new collector design,” IEEE Photon. Technol. Lett.20(13), 1163–1165 (2008). [CrossRef]
- D.-H. Jun, J.-H. Jang, I. Adesida, and J.-I. Song, “Improved efficiency bandwidth product of modified uni-traveling carrier photodiode structures using an undoped photo-absorption layer,” Jpn. J. Appl. Phys.45(4B), 3475–3478 (2006). [CrossRef]
- X. Wang, N. Duan, H. Chen, and J. C. Campbell, “InGaAs-InP photodiodes with high responsivity and high saturation power,” IEEE Photon. Technol. Lett.19(16), 1272–1274 (2007). [CrossRef]
- M. Chtioui, F. Lelarge, A. Enard, F. Pommereau, D. Carpentier, A. Marceaux, F. van Dijk, and M. Achouche, “High responsivity and high power UTC and MUTC GaInAs-InP photodiodes,” IEEE Photon. Technol. Lett.24(4), 318–320 (2012). [CrossRef]
- Z. Li, H. Pan, H. Chen, A. Beling, and J. C. Campbell, “High-saturation-current modified uni-traveling-carrier photodiode with cliff layer,” IEEE J. Quantum Electron.46(5), 626–632 (2010). [CrossRef]
- J.-W. Shi, F.-M. Kuo, and J. E. Bowers, “Design and analysis of ultra-high-speed near-ballistic uni-traveling-carrier photodiodes under a 50-Ω load for high-power performance,” IEEE Photon. Technol. Lett.24(7), 533–535 (2012). [CrossRef]
- J.-W. Shi, Y.-S. Wu, C.-Y. Wu, P.-H. Chiu, and C.-C. Hong, “High-speed, high-responsivity, and high-power performance of near-ballistic uni-traveling-carrier photodiode at 1.55-μm wavelength,” IEEE Photon. Technol. Lett.17(9), 1929–1931 (2005). [CrossRef]
- M. Chtioui, A. Enard, D. Carpentier, S. Bernard, B. Rousseau, F. Lelarge, F. Pommereau, and M. Achouche, “High-power and high-linearity uni-traveling-carrier photodiodes for analog photonic links,” IEEE Photon. Technol. Lett.20(3), 202–204 (2008). [CrossRef]
- H. Fukano, Y. Muramoto, K. Takahata, and Y. Matsuoka, “High efficiency edge-illuminated unitravelling-carrier-structure refracting-facet photodiode,” Electron. Lett.35(19), 1664–1665 (1999). [CrossRef]
- S. Demiguel, N. Li, X. Li, X. Zheng, J. Kim, J. C. Campbell, H. Lu, and A. Anselm, “Very high-responsivity evanescently coupled photodiodes integrating a short planar multimode waveguide for high-speed applications,” IEEE Photon. Technol. Lett.15(12), 1761–1763 (2003). [CrossRef]
- J. Klamkin, S. M. Madison, D. C. Oakley, A. Napoleone, F. J. O’Donnell, M. Sheehan, L. J. Missaggia, J. M. Caissie, J. J. Plant, and P. W. Juodawlkis, “Uni-traveling-carrier variable confinement waveguide photodiodes,” Opt. Express19(11), 10199–10205 (2011). [CrossRef] [PubMed]
- M. Hosseinifar, V. Ahmadi, and G. Abaeiani, “Microring-based unitraveling carrier photodiodes for high bandwidth-efficiency product photodetection in optical communication,” J. Lightwave Technol.29(9), 1285–1292 (2011). [CrossRef]
- J.-W. Shi, F.-M. Kuo, C.-J. Wu, C. L. Chang, C.-Y. Liu, C. Y. Chen, and J.-I. Chyi, “Extremely high saturation current-bandwidth product performance of a near-ballistic uni-traveling-carrier photodiode with a flip-chip bonding structure,” IEEE J. Quantum Electron.46(1), 80–86 (2010). [CrossRef]
- Y.-S. Wu, J.-W. Shi, and P.-H. Chiu, “Analytical modeling of a high-performance near-ballistic uni-traveling-carrier photodiode at a 1.55-μm wavelength,” IEEE Photon. Technol. Lett.18(8), 938–940 (2006). [CrossRef]
- R. Stratton, “Diffusion of hot and cold electrons in semiconductor barriers,” Phys. Rev.126(6), 2002–2014 (1962). [CrossRef]
- R. Stratton, “Semiconductor current-flow equations (diffusion and degeneracy),” IEEE Trans. Electron. Dev.19(12), 1288–1292 (1972). [CrossRef]
- New semiconductor materials, characteristics and properties, http://www.ioffe.rssi.ru/SVA/NSM/ .
- S. Adachi, Physical Properties of III–V Semiconductor Compounds InP, InAs, GaAs, GaP, InGaAs, and InGaAsP, (John Wiley and Sons, 1992).

## Cited By |
Alert me when this paper is cited |

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.

« Previous Article | Next Article »

OSA is a member of CrossRef.