Strongly enhanced THz emission caused by localized surface charges in semiconducting germanium nanowires

Woo Jung Lee; Jin Won Ma; Jung Min Bae; Kwang Sik Jeong; Mann Ho Cho; Chul Kang; Jung Sub Wi

doi:10.1038/srep01984

Strongly enhanced THz emission caused by localized surface charges in semiconducting germanium nanowires

Woo Jung Lee, Jin Won Ma, Jung Min Bae, Kwang Sik Jeong, Mann Ho Cho, Chul Kang, Jung Sub Wi

Department of Physics

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

31 Citations (Scopus)

Abstract

A principal cause of THz emission in semiconductor nanostructures is deeply involved with geometry, which stimulates the utilization of indirect bandgap semiconductors for THz applications. To date, applications for optoelectronic devices, such as emitters and detectors, using THz radiation have focused only on direct bandgap materials. This paper reports the first observation of strongly enhanced THz emission from Germanium nanowires (Ge NWs). The origin of THz generation from Ge NWs can be interpreted using two terms: high photoexcited electron-hole carriers (Δn) and strong built-in electric field (E b) at the wire surface based on the relation. The first is related to the extensive surface area needed to trigger an irradiated photon due to high aspect ratio. The second corresponds to the variation of Fermi-level determined by confined surface charges. Moreover, the carrier dynamics of optically excited electrons and holes give rise to phonon emission according to the THz region.

Original language	English
Article number	1984
Journal	Scientific reports
Volume	3
DOIs	https://doi.org/10.1038/srep01984
Publication status	Published - 2013

Bibliographical note

Funding Information:
This work was partially supported by the New and Renewable Energy R&D Program (Grant No: 2009T100100614) under the Ministry of Knowledge Economy and Metrology Research Center under Korea Research Institute of Standards and Science. Also, the Yonsei University Research Fund of 2012 for Post doctoral fellowship supported this work.

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title = "Strongly enhanced THz emission caused by localized surface charges in semiconducting germanium nanowires",

abstract = "A principal cause of THz emission in semiconductor nanostructures is deeply involved with geometry, which stimulates the utilization of indirect bandgap semiconductors for THz applications. To date, applications for optoelectronic devices, such as emitters and detectors, using THz radiation have focused only on direct bandgap materials. This paper reports the first observation of strongly enhanced THz emission from Germanium nanowires (Ge NWs). The origin of THz generation from Ge NWs can be interpreted using two terms: high photoexcited electron-hole carriers (Δn) and strong built-in electric field (E b) at the wire surface based on the relation. The first is related to the extensive surface area needed to trigger an irradiated photon due to high aspect ratio. The second corresponds to the variation of Fermi-level determined by confined surface charges. Moreover, the carrier dynamics of optically excited electrons and holes give rise to phonon emission according to the THz region.",

author = "Lee, {Woo Jung} and Ma, {Jin Won} and Bae, {Jung Min} and Jeong, {Kwang Sik} and Cho, {Mann Ho} and Chul Kang and Wi, {Jung Sub}",

note = "Funding Information: This work was partially supported by the New and Renewable Energy R&D Program (Grant No: 2009T100100614) under the Ministry of Knowledge Economy and Metrology Research Center under Korea Research Institute of Standards and Science. Also, the Yonsei University Research Fund of 2012 for Post doctoral fellowship supported this work.",

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AU - Ma, Jin Won

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AU - Jeong, Kwang Sik

AU - Cho, Mann Ho

AU - Kang, Chul

AU - Wi, Jung Sub

N1 - Funding Information: This work was partially supported by the New and Renewable Energy R&D Program (Grant No: 2009T100100614) under the Ministry of Knowledge Economy and Metrology Research Center under Korea Research Institute of Standards and Science. Also, the Yonsei University Research Fund of 2012 for Post doctoral fellowship supported this work.

PY - 2013

Y1 - 2013

N2 - A principal cause of THz emission in semiconductor nanostructures is deeply involved with geometry, which stimulates the utilization of indirect bandgap semiconductors for THz applications. To date, applications for optoelectronic devices, such as emitters and detectors, using THz radiation have focused only on direct bandgap materials. This paper reports the first observation of strongly enhanced THz emission from Germanium nanowires (Ge NWs). The origin of THz generation from Ge NWs can be interpreted using two terms: high photoexcited electron-hole carriers (Δn) and strong built-in electric field (E b) at the wire surface based on the relation. The first is related to the extensive surface area needed to trigger an irradiated photon due to high aspect ratio. The second corresponds to the variation of Fermi-level determined by confined surface charges. Moreover, the carrier dynamics of optically excited electrons and holes give rise to phonon emission according to the THz region.

AB - A principal cause of THz emission in semiconductor nanostructures is deeply involved with geometry, which stimulates the utilization of indirect bandgap semiconductors for THz applications. To date, applications for optoelectronic devices, such as emitters and detectors, using THz radiation have focused only on direct bandgap materials. This paper reports the first observation of strongly enhanced THz emission from Germanium nanowires (Ge NWs). The origin of THz generation from Ge NWs can be interpreted using two terms: high photoexcited electron-hole carriers (Δn) and strong built-in electric field (E b) at the wire surface based on the relation. The first is related to the extensive surface area needed to trigger an irradiated photon due to high aspect ratio. The second corresponds to the variation of Fermi-level determined by confined surface charges. Moreover, the carrier dynamics of optically excited electrons and holes give rise to phonon emission according to the THz region.

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Strongly enhanced THz emission caused by localized surface charges in semiconducting germanium nanowires

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