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11	Direct Nano-Patterning With Nano-Optic Devices Meenashi Sundaram, Vijay 2010 May 1900 (has links) In this study nano-patterning was carried out using two different nano-optic devices namely- the NSOM and Fresnel zone plate. In the first study, NSOM was used to generate nano-patterns on selected semiconducting (Si and Ge) and metallic (Cr, Cu and Ag) targets under different laser pulse durations, laser energies and number of laser pulses. Based on the experimental results, femtosecond laser pulses, provided lower pattern generation thresholds on targets but higher damage thresholds to the NSOM probes at the wavelength (~400-410 nm) studied, compared with nanosecond laser pulses. Three different mechanisms were identified as the dominant processes for pattern generation under different conditions, namely nano-scale laser ablation, nano-scale thermal oxidation and nano-scale melting/recrystallization of the targets. Furthermore, the resulting nano-patterns also showed a significant dependence on the optical properties (i.e., absorption coefficient and surface reflectivity) of the target material. By comparing the obtained experimental results, it was concluded that the optical energy transport from the NSOM probe to the target dominates the pattern generation when femtosecond laser is applied to the NSOM system. When nanosecond laser is applied, both the thermal and optical energy transported from the NSOM probe to the targets attribute to the obtained morphology of nano-patterns on different targets under the experimental conditions studied. In the second study, a traditional Fresnel zone plate with a focus length of 3 micrometres was fabricated with a novel lift-off process in e-beam lithography. The fabrication process involved, using a HSQ/PMMA bi-layer in a negative tone lift-off process with a layer of conducting polyaniline for charge dissipation. HSQ was used as the high resolution negative resist for e-beam patterning and the PMMA under-layer was used to enable a HSQ lift-off process. The fabricated Fresnel zone plate was used to generate nano-patterns on a UV sensitive photoresist using nanosecond laser light with lamda~409nm. The smallest pattern sizes generated was close to the diffraction limit. Nano-pattern sizes generated on the photoresist were comparable with a numerically calculated intensity distribution at the focus spot of the designed Fresnel zone plate obtained from Scalar Diffraction Theory. near field energy transport nano-crater nano-protrusion nano-crystallization nano laser ablation nano-oxidation fresnel zone plate e-beam lithography scalar diffraction theory
12	Cryogenic Etching of the Electroplating Mold for Improved Zone Plate Lenses Larsson, Daniel January 2010 (has links) The fabrication of zone plate lenses that are used for focusing X-rays relies on nanofabrication techniques such as e-beam lithography, reactive ion etching, and electroplating. The circular grating-like zone plate pattern can have a smallest half-period, a so-called zone width, of down to 20 nm while it also needs to have a height that is 5 to 10 times the zone width to have good diffraction efficiency. This high aspect ratio structuring is a very challenging field of nanofabrication. This diploma project has focused on improving the process step of fabricating the electroplating mold by cryo-cooling the polymer during the reactive ion etching with O2. The low temperature causes passivation of the sidewalls of the mold during etching which results in a more ideal rectangular profile of the high aspect ratio plating mold. By etching at -100 °C, structures with highly vertical sidewalls and no undercut were realized. The experiments showed that there is a tradeoff between the anisotropy of the zone profile and the formation rate of polymer residue, so-called RIE grass. Through a proper choice of process parameters the grass could be completely removed without introducing any undercut. / QC 20100414 etching plasma etching zone plate x-ray nanofabrication sidewall passivation cryo cryogenic undercut Other Engineering and Technologies Annan teknik Condensed Matter Physics Den kondenserade materiens fysik
13	Multilagenbasierte Transmissionsoptiken für die Röntgenmikroskopie / Multilayer based transmission optics for x-ray microscopy Liese, Tobias 15 May 2012 (has links) No description available. 530 Physik RD 000 RP 000 RRE 000 RVC 000 RVS 000 RXE 000 Physics Gepulste Laserdeposition Fokussierte Ionenstrahltechnik Röntgenmikroskopie Zonenplatte Multilagen-Laue-Linse Multilagen-Zonenplatte dünne Schichten Grenzflächen kumulative Rauigkeit Glättung pulsed laser deposition focused ion beam x-ray microscopy x-ray optics zone plate multilayer Laue lens multilayer zone plate thin films interface cumulative roughness smoothing 33.00 33.18 33.68 33.79

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