Carrier dynamics and terahertz photoconductivity of doped silicon measured by femtosecond pump-terahertz probe spectroscopy

  • QingLi Zhou
  • YuLei Shi
  • Tong Li
  • Bin Jin
  • DongMei Zhao
  • CunLin Zhang


The carrier dynamics and terahertz photoconductivity in the n-type silicon (n-Si) as well as in the p-type Silicon (p-Si) have been investigated by using femtosecond pump-terahertz probe technique. The measurements show that the relative change of terahertz transmission of p-Si at low pump power is slightly smaller than that of n-Si, due to the lower carrier density induced by the recombination of original holes in the p-type material and the photogenerated electrons. At high pump power, the bigger change of terahertz transmission of p-Si originates from the greater mobility of the carriers compared to n-Si. The transient photoconductivities are calculated and fit well with the Drude-Smith model, showing that the mobility of the photogenerated carriers decreases with the increasing pump power. The obtained results indicate that femtosecond pump-terahertz probe technique is a promising method to investigate the carrier dynamics of semiconductors.


semiconductor terahertz carrier dynamics 


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  1. 1.
    Averitt R D, Taylor A J. Ultrafast optical and far-infrared quasiparticle dynamics in correlated electron materials. J Phys-Condens Matter, 2002, 14: R1357–R1390CrossRefADSGoogle Scholar
  2. 2.
    Beard M C, Turner G M, Schmuttenmaer C A. Transient photoconductivity in GaAs as measured by time-resolved terahertz spectroscopy. Phys Rev B, 2000, 62: 15764–15777CrossRefADSGoogle Scholar
  3. 3.
    Prabhu S S, Ralph S E, Melloch M R, et al. Carrier dynamics of low-temperature-grown GaAs observed via THz spectroscopy. Appl Phys Lett, 1997, 70: 2419–2421CrossRefADSGoogle Scholar
  4. 4.
    Liu K P H, Hegmann F A. Ultrafast carrier relaxation in radiation- damaged silicon on sapphire studied by optical-pump-terahertz- probe experiments. Appl Phys Lett, 2001, 78: 3478–3480CrossRefADSGoogle Scholar
  5. 5.
    Shi Y, Xu X, Yang Y, et al. Anomalous enhancement of terahertz radiation from semi-insulating GaAs surfaces induced by optical pump. Appl Phys Lett, 2006, 89: 081129CrossRefADSGoogle Scholar
  6. 6.
    Parkinson P, Lloyd-Hughes J, Gao Q, et al. Transient terahertz conductivity of GaAs nanowires. Nano Letters, 2007, 7: 2162–2165CrossRefADSGoogle Scholar
  7. 7.
    Knoesel E, Bonn M, Shan J, et al. Charge transport and carrier dynamics in liquids probed by THz time-domain spectroscopy. Phys Rev Lett, 2001, 86: 340–343CrossRefADSGoogle Scholar
  8. 8.
    Abuabara S G, Cady C W, Baxter J B, et al. Ultrafast photooxidation of Mn(II)-Terpyridine complexes covalently attached to TiO2 nanoparticles. J Phys Chem C, 2007, 111: 11982–11990CrossRefGoogle Scholar
  9. 9.
    Averitt R D, Lobad A I, Kwon C, et al. Ultrafast conductivity dynamics in colossal magnetoresistance manganites. Phys Rev Lett, 2001, 87: 017401CrossRefADSGoogle Scholar
  10. 10.
    Xie X, Dai J, Zhang X-C. Coherent control of THz wave generation in ambient air. Phys Rev Lett, 2006, 96: 075005CrossRefADSGoogle Scholar
  11. 11.
    Wu Q, Litz M, Zhang X-C. Broadband detection capability of ZnTe electro-optic field detectors. Appl Phys Lett, 1996, 68: 2924–2926CrossRefADSGoogle Scholar
  12. 12.
    Sosnowski T S, Norris T B, Wang H H, et al. High-carrier-density electron dynamics in low-temperature-grown GaAs. Appl Phys Lett, 1997, 70: 3245–3247CrossRefADSGoogle Scholar
  13. 13.
    Lloyd-Hughes J, Merchant S K E, Fu L, et al. Influence of surface passivation on ultrafast carrier dynamics and terahertz radiation generation in GaAs. Appl Phys Lett, 2006, 89: 232102CrossRefADSGoogle Scholar
  14. 14.
    Cooke D G, Hegmann F A, Young E C, et al. Electron mobility in dilute GaAs bismide and nitride alloys measured by time-resolved terahertz spectroscopy. Appl Phys Lett, 2006, 89: 122103CrossRefADSGoogle Scholar
  15. 15.
    Walther M, Cooke D G, Sherstan C, et al. Terahertz conductivity of thin gold films at the metal-insulator percolation transition. Phys Rev B, 2007, 76: 125408CrossRefADSGoogle Scholar
  16. 16.
    Prasankumar R P, Scopatz A, Hilton D J, et al. Carrier dynamics in self-assembled ErAs nanoislands embedded in GaAs measured by optical-pump terahertz-probe spectroscopy. Appl Phys Lett, 2005, 86: 201107CrossRefADSGoogle Scholar
  17. 17.
    Aspnes D E, Studna A A. Dielectric functions and optical parameters of Si, Ge, GaP, GaAs, GaSb, InP, InAs, and InSb from 1. 5 to 6.0 eV. Phys Rev B, 1983, 27: 985–1009CrossRefADSGoogle Scholar
  18. 18.
    Baxter J B, Schmuttenmaer C A. Conductivity of ZnO nanowires, nanoparticles, and thin films using time-resolved terahertz spectroscopy. J Phys Chem B, 2006, 110: 25229–25239CrossRefGoogle Scholar
  19. 19.
    Smith N V. Classical generalization of the Drude formula for the optical conductivity. Phys Rev B, 2001, 64: 155106CrossRefADSGoogle Scholar
  20. 20.
    Beard M C, Turner G M, Murphy J E, et al. Electronic coupling in InP nanoparticle arrays. Nano Lett, 2003, 3: 1695–1699CrossRefADSGoogle Scholar

Copyright information

© Science in China Press and Springer Berlin Heidelberg 2009

Authors and Affiliations

  • QingLi Zhou
    • 1
  • YuLei Shi
    • 1
  • Tong Li
    • 2
  • Bin Jin
    • 1
  • DongMei Zhao
    • 1
  • CunLin Zhang
    • 1
  1. 1.Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Department of PhysicsCapital Normal UniversityBeijingChina
  2. 2.Department of Electronics EngineeringTianjin University of Technology and EducationTianjinChina

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