Ultrabroadband Terahertz Near-Field Nanospectroscopy with a HgCdTe Detector.
ACS Photonics
; 10(12): 4329-4339, 2023 Dec 20.
Article
em En
| MEDLINE
| ID: mdl-38145170
ABSTRACT
While near-field infrared nanospectroscopy provides a powerful tool for nanoscale material characterization, broadband nanospectroscopy of elementary material excitations in the single-digit terahertz (THz) range remains relatively unexplored. Here, we study liquid-Helium-cooled photoconductive Hg1-XCdXTe (MCT) for use as a fast detector in near-field nanospectroscopy. Compared to the common T = 77 K operation, liquid-Helium cooling reduces the MCT detection threshold to â¼22 meV, improves the noise performance, and yields a response bandwidth exceeding 10 MHz. These improved detector properties have a profound impact on the near-field technique, enabling unprecedented broadband nanospectroscopy across a range of 5 to >50 THz (175 to >1750 cm-1, or <6 to 57 µm), i.e., covering what is commonly known as the "THz gap". Our approach has been implemented as a user program at the National Synchrotron Light Source II, Upton, USA, where we showcase ultrabroadband synchrotron nanospectroscopy of phonons in ZnSe (â¼7.8 THz) and BaF2 (â¼6.7 THz), as well as hyperbolic phonon polaritons in GeS (6-8 THz).
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MEDLINE
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En
Ano de publicação:
2023
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Article