Enhanced nonlinear response by surface carrier excitation of metal-patterned semiconductors
Young-Mi Bahk1*
1Department of Physics, Incheon National University, Incheon 443-803, Korea
* Presenter:Young-Mi Bahk
Since a variety of direct-gap semiconductors has an electronic band gap corresponding to a photon energy in the visible or near-visible spectrum of light, and terahertz waves enables to characterize electrical properties with a low photon energy with picosecond temporal resolution, optical pump-terahertz probe spectroscopy has been an useful tool for studies of semiconductor carrier dynamics in a ultrafast time scale. Recently, we suggested terahertz nano-probing system based on the metallic nanogap patterned onto the target semiconductors in order to observe the surface carrier dynamics. Metallic nanogaps facilitate strong field confinement of terahertz waves in a nanoscale and observation of optical properties near the surface of the target materials. In this work, we measured time resolved terahertz transmission change by the surface photo-excited carriers in nanogap-patterned semiconductors and describe the surface carrier life time and enhanced absorption.

[1] G. Choi et al., Nano Lett. 17(10), 6397 (2017)
[2] G. Choi et al., ACS Photon. DOI: 10.1021/acsphotonics.8b00724 (2018)

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