Optical characterization of gold-cuprous oxide interfaces for terahertz emission applications

Journal article (2014)
Department
ImPhys/Imaging Physics (AS) (TU Delft)
Copyright: © 2014 Optical Society of America
DOI: https://doi.org/doi:10.1364/AO.53.001994
Thin films, optical properties Spectroscopy, terahertz Thin films, other properties Ellipsometry and polarimetry
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Published Date

24-03-2014

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Source:

Applied Optics, 53 (10), 2014

ISSN:

1559-128X

Source:

http://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-53-10-1994

Faculty

Applied Sciences

Department

ImPhys/Imaging Physics

Abstract

We show that the interface between gold and thermally formed cuprous oxide, which emits terahertz radiation when illuminated with ultrafast femtosecond lasers, is in fact an AuCu/Cu2O interface due to the formation of the thermal diffusion alloy AuCu. The alloy enables the formation of a Schottky-barrier-like electric field near the interface which is essential to explain the THz emission from these samples. We confirm the formation of this AuCu layer by x-ray diffraction measurements, ellipsometry, and visual inspection. We determined the frequency-dependent complex refractive indices of the Cu2O and AuCu layer and verified them using reflection spectroscopy measurements. These refractive indices can be used for optimizing the thickness of Cu2O for maximum THz emission from these interfaces.