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 Karl Franzens University Graz

Graz University of Technology 

Nanoscale Cross-sectional Extreme-UV imaging
Prof. Dr. Gerhard G. Paulus
FSU Jena & Helmholtz Institut
16:15 - 17:15 Tuesday 30 April 2024 TUG

I will discuss nanoscale imaging in the extreme ultraviolet (XUV) spectral region using high-harmonics produced by femtosecond laser radiation. The imaging method to be discussed is the XUV incarnation of optical coherence tomography (OCT), which, in turn, was invented in Austria by A. Fercher. However, due to the challenges of XUV optics, XUV coherence tomography (XCT) has to be implemented in a vastly different way — but it also offers special capabilities.

A particularly relevant application of XCT for the spectral range up to 100 eV are silicon-based samples. We have demonstrated depth resolutions of 20 nm and very high sensitivities. Buried oxide layers of a thickness of a few nanometers could be detected as well as buried monolayers of graphene. It is even possible to identify the material encapsulated in silicon and determine properties like layer roughness without destroying the sample. A unique perspective is ultrafast imaging.