Highlighted authors are members of the University of Jena.
In situ current measurement in a compact broad ion source for helium and other ions
Year of publicationStatusReview pendingPublished in:Vacuum : surface engineering, surface instrumentation & vacuum technology
J. Kaufmann, F. Otto, T. Siefke, U. Zeitner
Adaptive LED illumination with maskless irregular lenslet arrays and controlled crosstalk
Year of publicationPublished in:Journal of optical microsystems
D. Stefanidi, L. Wilhelm, P. Schreiber, P. Schleicher, S. Kleinle, R. Rosenberger, F. Kraze, R. Brüning, A. Tünnermann
Multi-spectral analyses in the VIS-NIR-SWIR for detection of ideal harvesting time and degree of ripeness
Year of publicationPublished in:Photonic Technologies in Plant and Agricultural Science II: 29–30 January 2025 San Francisco, California, United States
A. Ruvalcaba-Perez, G. Siess, N. Janunts, V. Boehm, A. Tuennermann
Manufacturing Process and Characteristics of Silica Nanostructures for Anti-Reflection at 355 nm
Year of publicationPublished in:Coatings
A. Gärtner, M. Mureșan, C. Mühlig, T. Herffurth, N. Felde, H. Wagner, U. Schulz, A. Bingel, S. Schröder, T. Mocek, A. Tünnermann
Second harmonic generation in iridium and iridium/Al₂O₃ heterostructure coatings
Year of publicationPublished in:Optical Materials Express
P. Paul, R. Rafi, S. Beer, O. Ghaebi, S. Klimmer, G. Soavi, S. Nolte, S. Schröder, A. Tünnermann, A. Szeghalmi
Submicrometer Defect Detection and Classification by Angle Resolved Light Scattering
Year of publicationStatusReview pendingPublished in:Optical Interference Coatings, OIC 2025 in Proceedings Optica OIC - Optical Interference Coatings Conference 2025
S. Schröder, A. Munser, S. Ma, T. Herffurth, T. Gischkat, C. Mühlig, A. Tünnermann
W/Si Multilayer Mirrors for Soft X-Ray Wavelengths < 2.4 nm
Year of publicationStatusReview pendingPublished in:Surfaces
D. Sevriukov, S. Yulin, S. Schröder, A. Tünnermann
W/Si multilayer mirrors are a promising candidate for soft X-ray applications at wavelengths below 2.4 nm. However, their optical performance is strongly affected by interface roughness and interlayer mixing, which limits reflectivity. One approach to improving interface quality is the application of BIAS voltage during deposition. In this study, W/Si multilayer mirrors with bilayer thickness of ~1.5 nm and 100 bilayers were fabricated using DC magnetron sputtering, with ion assistance of 75 V, 100 V, and 200 V applied during the deposition of silicon layers. Grazing incidence X-ray reflectivity (GIXR) measurements at Cu Kα (λ = 0.154 nm) showed that applying BIAS ≤ 100 V reduced interface roughness and increased reflectivity, with a maximum effect observed at 75 V. In contrast, at 200 V, strong diffusion intermixing reduced the bilayer thickness to 1.29 nm and nearly eliminated reflectivity. Soft X-ray reflectivity measurements at λ ~ 1.5 nm confirmed that ion assistance improved optical performance, increasing mirror reflectivity from ~1% (BIAS = 0 V) to ~2.3% (BIAS = 75 V). Atomic force microscopy (AFM) measurements also demonstrated a reduction in surface roughness from 0.22 nm to 0.11 nm due to using ion assistance. These results indicate that moderate ion assistance (<100 V) can enhance the optical quality of W/Si multilayer mirrors by reducing interface roughness, while excessive BIAS (>100 V) leads to diffusion intermixing and optical degradation. The novelty of this work lies in the direct application and variation in BIAS voltage during Si-layer growth, enabling detailed investigation of its influence on interface roughness and reflectivity. This approach provides a simple and effective tool for optimizing the performance of W/Si multilayer mirrors for soft X-ray applications.
