Ultrafast carrier dynamics in Ge by ultra-broadband mid-infrared probe spectroscopy

Tien Tien Yeh; Hideto Shirai; Chien-Ming Tu; Takao Fuji; Takayoshi Kobayashi; Chih-Wei Luo

doi:10.1038/srep40492

Ultrafast carrier dynamics in Ge by ultra-broadband mid-infrared probe spectroscopy

Tien Tien Yeh, Hideto Shirai, Chien-Ming Tu, Takao Fuji, Takayoshi Kobayashi, Chih-Wei Luo^*

^*Corresponding author for this work

Department of Electrophysics

Research output: Contribution to journal › Article › peer-review

24 Scopus citations

Abstract

In this study, we carried out 800-nm pump and ultra-broadband mid-infrared (MIR) probe spectroscopy with high time-resolution (70 fs) in bulk Ge. By fitting the time-resolved difference reflection spectra [δR(ω)/R(ω)] with the Drude model in the 200-5000 cm^-1 region, the time-dependent plasma frequency and scattering rate have been obtained. Through the calculation, we can further get the time-dependent photoexcited carrier concentration and carrier mobility. The Auger recombination essentially dominates the fast relaxation of photoexcited carriers within 100 ps followed by slow relaxation due to diffusion. Additionally, a novel oscillation feature is clearly found in time-resolved difference reflection spectra around 2000 cm^-1 especially for high pump fluence, which is the Lorentz oscillation lasting for about 20 ps due to the Coulomb force exerted just after the excitation.

Original language	American English
Article number	40492
Journal	Scientific reports
Volume	7
DOIs	https://doi.org/10.1038/srep40492
State	Published - 11 Jan 2017

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title = "Ultrafast carrier dynamics in Ge by ultra-broadband mid-infrared probe spectroscopy",

abstract = "In this study, we carried out 800-nm pump and ultra-broadband mid-infrared (MIR) probe spectroscopy with high time-resolution (70 fs) in bulk Ge. By fitting the time-resolved difference reflection spectra [δR(ω)/R(ω)] with the Drude model in the 200-5000 cm-1 region, the time-dependent plasma frequency and scattering rate have been obtained. Through the calculation, we can further get the time-dependent photoexcited carrier concentration and carrier mobility. The Auger recombination essentially dominates the fast relaxation of photoexcited carriers within 100 ps followed by slow relaxation due to diffusion. Additionally, a novel oscillation feature is clearly found in time-resolved difference reflection spectra around 2000 cm-1 especially for high pump fluence, which is the Lorentz oscillation lasting for about 20 ps due to the Coulomb force exerted just after the excitation.",

author = "Yeh, {Tien Tien} and Hideto Shirai and Chien-Ming Tu and Takao Fuji and Takayoshi Kobayashi and Chih-Wei Luo",

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T1 - Ultrafast carrier dynamics in Ge by ultra-broadband mid-infrared probe spectroscopy

AU - Yeh, Tien Tien

AU - Shirai, Hideto

AU - Tu, Chien-Ming

AU - Fuji, Takao

AU - Kobayashi, Takayoshi

AU - Luo, Chih-Wei

PY - 2017/1/11

Y1 - 2017/1/11

N2 - In this study, we carried out 800-nm pump and ultra-broadband mid-infrared (MIR) probe spectroscopy with high time-resolution (70 fs) in bulk Ge. By fitting the time-resolved difference reflection spectra [δR(ω)/R(ω)] with the Drude model in the 200-5000 cm-1 region, the time-dependent plasma frequency and scattering rate have been obtained. Through the calculation, we can further get the time-dependent photoexcited carrier concentration and carrier mobility. The Auger recombination essentially dominates the fast relaxation of photoexcited carriers within 100 ps followed by slow relaxation due to diffusion. Additionally, a novel oscillation feature is clearly found in time-resolved difference reflection spectra around 2000 cm-1 especially for high pump fluence, which is the Lorentz oscillation lasting for about 20 ps due to the Coulomb force exerted just after the excitation.

AB - In this study, we carried out 800-nm pump and ultra-broadband mid-infrared (MIR) probe spectroscopy with high time-resolution (70 fs) in bulk Ge. By fitting the time-resolved difference reflection spectra [δR(ω)/R(ω)] with the Drude model in the 200-5000 cm-1 region, the time-dependent plasma frequency and scattering rate have been obtained. Through the calculation, we can further get the time-dependent photoexcited carrier concentration and carrier mobility. The Auger recombination essentially dominates the fast relaxation of photoexcited carriers within 100 ps followed by slow relaxation due to diffusion. Additionally, a novel oscillation feature is clearly found in time-resolved difference reflection spectra around 2000 cm-1 especially for high pump fluence, which is the Lorentz oscillation lasting for about 20 ps due to the Coulomb force exerted just after the excitation.

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Ultrafast carrier dynamics in Ge by ultra-broadband mid-infrared probe spectroscopy

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