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An Investigation of the Stresses Causing the Spontaneous Delamination of Titanium-Platinum Bilayers Leading to The Formation of NanogapsAlBatati, Afnan 23 July 2020 (has links)
Adhesion lithography has been used to pattern nanogaps between two electrodes of the same or different metals onto a substrate. Patterning Al and Ti/Pt bilayer electrodes have been shown to form nanogaps leaving behind relatively consistent nanogaps of less than 12 nm between the electrodes. These nanogaps are formed without the need for adhesion lithography due to the bilayer spontaneously delaminating from the aluminum electrodes, In this study, the stresses in the Ti/Pt bilayer are investigated to determine the amount of stress required for delamination and the properties causing it. The goal is to recreate this stress mechanism in other patterned metals such as Au and Al. Heat cycling is used to induce high stress in other metal electrode combinations in an attempt to induce spontaneous delamination in Al and Au but fails up to 310°C annealing temperature. Theoretical methods are used to determine the stress: searching for an appropriate mathematical model and using finite element analysis in ABAQUS software to create a simulation of the delaminating Ti/Pt bilayer. The stress is found to be caused by the residual stresses in platinum and the high energy e-beam deposition method. An experimental value for the stress and the ability to recreate it in other metals remains elusive.
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Large Area Nanostructured Electronics Enabled Via Adhesion LithographyLoganathan, Kalaivanan 09 1900 (has links)
The fifth and sixth generations of mobile communications and the internet of things (IoT) demand high-performance electronic devices made at low cost over a large area. Unlike the conventional Si-based electronics, the emerging large-area electronics (LAE) require flexible, stretchable, and lightweight devices that are printable and able to mass manufacture without compromising the performance of state-of-the-art electronic devices. Hence, there is a quest to find alternative fabrication routes and conventional photolithography. In this research work, we explored the adhesion lithography (a-Lith) to further simplify the process steps by adapting bi-layer metals to induce intrinsic stress in the bi-layer and hence facilitate the self-peeling of metal layers which results in more uniform and smaller nanogap between two metals than the previously established a-Lith fabricated nanogaps. The nanogap metal electrodes are further used to fabricate radio frequency (RF) Schottky diodes made using a printable metal oxide semiconductor and flashlight annealing over wafer-scale and demonstrate the operation frequencies above 100 GHz/47 GHz (intrinsic/extrinsic). Notably, for the first time, photonic annealing on such an ultra-small (< 20 nm) nanoscale channel was demonstrated, and the rapid manufacturing of RF diodes from the solution route was achieved. On the other hand, for the first time, organic diodes made using a-Lith fabricated nanogap metal electrodes, and high mobility polymer semiconductors with molecular dopants showed an extrinsic cut-off frequency well above 14 GHz. Finally, the nanogap metal electrodes were explored as a mold and shadow mask to fabricate nano-feature soft stamp and nano-fluidic channels (NFC), respectively. The soft stamp can replicate the high aspect ratio nanoscale features on any arbitrary substrates using available soft lithography routes, and the NFC is further envisioned for bio-molecules detection and sensing applications.
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