Eliminating the reststrahlenband: Broadband THz emission from photoconductive THz emitters based on Ge and GeSn

Stephan F. Winnerl

doi:10.1117/12.3016406

18 June 2024 Eliminating the reststrahlenband: Broadband THz emission from photoconductive THz emitters based on Ge and GeSn

Stephan F. Winnerl

Author Affiliations +

Proceedings Volume PC12994, Terahertz Photonics III; PC1299407 (2024) https://doi.org/10.1117/12.3016406
Event: SPIE Photonics Europe, 2024, Strasbourg, France

Abstract

We present photoconductive emitters for broadband THz emission based on Ge and GeSn. Ge is attractive for this purpose due to its high carrier mobility and because of the absence of infrared-active phonons that suppress the THz emission. Emitters based on Ge, with Au trapping centers for carrier lifetime reduction, excited with 11 fs near-infrared pulses emit gapless THz spectra extending up to 70 THz. For excitation at the telecom wavelength 1550 nm a slight reduction of the bandgap of Ge is desirable. We show that this can be achieved in layers of GeSn with 2 % of Sn, grown by molecular beam epitaxy on Si. THz devices on a silicon platform offer the perspective to develop CMOS compatible THz systems with photonic integration both for the near-infrared radiation and the broadband THz radiation.

Conference Presentation

Citation Download Citation

Stephan F. Winnerl "Eliminating the reststrahlenband: Broadband THz emission from photoconductive THz emitters based on Ge and GeSn", Proc. SPIE PC12994, Terahertz Photonics III, PC1299407 (18 June 2024); https://doi.org/10.1117/12.3016406

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