The formation of a functional surfaces combines the properties of a substrate and monolayer to produce a new hybrid that can combine aspects of each. Monolayers can be made on many surfaces, and well defined functionalized monolayers were assembled on for silicon(111) and polydicyclopentadiene (PDCPD). Acid terminated monolayers were assembled on silicon(111) and their functionalization chemistry explored. It was shown that using trifluoroacetic anhydride to generate an intermediate reactive anhydride, the surface could be functionalized with amines. It was further shown that using soft lithography these functionalized surfaces could be patterned. Mixed monolayers of methyl and olefin terminated surfaces on silicon(111) were used to develop a new soft lithographic technique with polydimethylsiloxane (PDMS). PDMS can be controllably etched using fluoride species. The surface is first activated by the attachment of the Grubbs' 1st generation catalyst. A PDMS microfluidic device is then placed on the surface. By using a cross metathesis reaction, the exposed channel can be pacified. The next step, a fluoride etchant is used to remove PDMS, exposing an unreacted surface. Polymer brushes were then grown by ring opening metathesis polymerization (ROMP) in this region. Functionalization of the emerging polymer PDCPD was conducted through two different routes. ROMP formed PDCPD has double bonds that can be functionalized. In the first process, the double bonds were reacted with bromine. This is a rapid reaction and proceeds to a significant depth in the material. Bromines can then be displaced with amines in a substitution reaction. This was demonstrated with a fluorinated amine that when examined by XPS were shown to be present only at the surface, further more we were able to pattern this surface too. Secondly, a process using epoxides was developed. The epoxidation reaction could not be quantified, but formation in the second step of an amine functionalized surfaces was observed by XPS. Further reaction of surface hydroxyls was also observed. This was also used to grow polyethylimine from the surface to sufficient thickness that it became observable by infrared spectroscopy.

This work focuses on binary chemical nano-patterning and on aspects related to the self-organization and stability during and after dewetting of thin block-copolymer films on chemically nano-patterned substrates. Regarding surface functionalization with thiols, the exchange of thiols in both liquid and gas phase was first investigated. The aim was to control thiols-assembly on gold and thus to fabricate unscrambled binary chemical nano-patterns. The systems gold-thiols are considered as alternatives to silicon oxide-silanes systems in the chemical nano-patterning processes because of fabrication simplicity reasons. The strategy developed to avoid thiol exchange was used to fabricate unscrambled binary chemical nano-patterns combining a top-down approach, Electron Beam Lithography (EBL), and a bottom-up approach based on the self-assembly of thiols on gold. Than, using the chemically nano-patterned surfaces previously developed, the organization processes of thin block-copolymer films were studied. Thin symmetric and asymmetric diblock copolymer films were deposited on engineered substrates consisting of alternating less and more wettable stripes. By locally tuning the chemical properties of the substrate, the interaction potential between the polymer and the substrate can be manipulated. It was thus possible to force a liquid film to dewet or to self-organize in a variety of configurations through phase preparation, specific interactions, confinement.

New methods to fabricate nanometer sized structures will be a major driving force in transforming nanoscience to nanotechnology. There are numerous examples of the incorporation of nanoscale structures or materials enhancing the functionality of a device. Graphitic carbon is a widely used material in electroanalysis due to a number of advantageous properties such as wide potential window, low cost, mechanical stability, and applicability to many common redox systems. In this thesis, the fabrication of nanometer sized graphitic carbon structures is described. These structures were fabricated by using a combination of electron-beam lithography (EBL) and pyrolysis. EBL allows for the precise control of shape, size and location of these carbon nanostructures. The structure and electrochemical reactivity of thin films of the pyrolyzed material is initially examined. The methodology to fabricate nanosized carbon structures and the structural and electrical characterization of the nanostructure is presented. The nanometer sized carbon structures fabricated in this work are being applied as nanoelectrodes. For nanoband structures, we observe a limiting current plateau which is characteristic of radial diffusion to cylindrical ultramicroelectrodes. Their voltammetric behaviour shows good agreement with classical theoretical predictions. Both carbon film and nanoband electrodes have been used as substrates for metal electrodeposition. The size and morphology of the deposited Au particles depends greatly on the substrate. On the nanoband electrodes, the Au particles exhibit a multi-branched or dendridic morphology. Their size and surface area are much larger than those electrodeposited on the carbon film electrode under the same conditions. The surface enhanced Raman spectroscopy (SERS) properties of the gold deposited on the nanobands was studied. A high enhancement in Raman intensity for a molecular layer on the nanoband supported gold is observed.

<p>Couplers are one of the most frequently used passive devices in microwave circuitry. The main function of a coupler is to divide (or combine) a radio frequency signal into (from) two separate signals by a specific ratio and phase difference. With the need for smaller electronic devices, a reduction in the area of a distributed coupler would prove to be valuable. The purpose of this research is to develop, simulate, fabricate and test high aspect ratio microstructure couplers that are smaller in area than existing distributed couplers, and have comparable or better performance. One method used to reduce the area of a distributed coupler is to replace single or multiple transmission lines with lumped element equivalent circuits. One category of lumped elements that has not been extensively implemented is high aspect ratio lumped elements. High aspect ratio lumped elements fabricated with deep X-ray lithography are able to take advantage of using the vertical dimension, and reduce their planar area. In this thesis high aspect ratio lumped elements are used in the design of 3-dB microstructure couplers that show significant area reduction compared to equivalent distributed couplers.</p> <p>The designs of the microstructure couplers were based on the lumped element equivalent circuits of a 3-dB branch-line and a 3-dB rat-race distributed coupler. Simulations were performed to determine the lumped element values that would provide the largest 3-dB bandwidth while still maintaining close to ideal coupling and through values, return loss bandwidth, isolation bandwidth, and phase. These lumped element values were then implemented in the microstructure coupler designs as high aspect ratio microstructure lumped elements. 3-D electromagnetic simulations were performed which verified that the structures behaved electrically as couplers. The microstructure couplers were designed to be 220 &#x00B5;m tall nickel structures with capacitance gap widths of 6 µm.</p> <p>Fabrication of the microstructure couplers using deep X-ray lithography was performed by the microfabrication group at IMT/KIT in Karlsruhe, Germany. Before testing, detailed visual inspection and the etching of the structures was performed at the Canadian Light Source.</p> <p>A total of five microstructure couplers were tested. Four of the tested couplers were based on the 3-dB branch-line coupler, and the fifth coupler was based on the 3-dB rat-race coupler. The microstructure branch-line design that had the best overall results was fabricated on quartz glass substrate and had an operation frequency of 5.3 GHz. The 3-dB bandwidth of the coupler was measured to be better than 75.5% and extrapolated to be 95.0%. At the centre frequency the through and coupled values were -4.32 dB and -4.44 dB. The phase difference between the couplers output ports was designed to be 90.0° and was measured to be 95.8°. The ±5° phase bandwidth was measured to be 12.7% and the isolation bandwidth was 28.8%. The measured results from the other couplers were comparable to simulation results.</p> <p>The main advantage of the microstructure coupler designs over existing distributed couplers is that the microstructure couplers show a significant area reduction. The branch-line microstructure designs were at least 85% smaller in area than their distributed equivalent on quartz glass. The rat-race microstructure design showed an area reduction of 90% when compared to its distributed equivalent on quartz glass.</p>

Microelectromechanical systems (MEMS) devices have been increasing in popularity for radio frequency (RF) and microwave communication systems due to the ability of MEMS devices to improve the performance of these circuits and systems. This interdisciplinary field combines the aspects of lithographic fabrication, mechanics, materials science, and RF/microwave circuit technology to produce moving structures with feature dimensions on the micron scale (micro structures). MEMS technology has been used to improve switches, varactors, and inductors to name a few specific examples. Most MEMS devices have been fabricated using planar micro fabrication techniques that are similar to current IC fabrication techniques. These techniques limit the thickness of individual layers to a few microns, and restrict the structures to have planar and not vertical features. <p> One micro fabrication technology that has not seen much application to microwave MEMS devices is LIGA, a German acronym for X-ray lithography, electroforming, and moulding. LIGA uses X-ray lithography to produce very tall structures (hundreds of microns) with excellent structural quality, and with lateral feature sizes smaller than a micron. These unique properties have led to an increased interest in LIGA for the development of high performance microwave devices, particularily as operating frequencies increase and physical device size decreases. Existing work using LIGA for microwave devices has concentrated on statically operating structures such as transmission lines, filters, and couplers. This research uses these unique fabrication capabilities to develop dynamically operating microwave devices with high frequency performance. <p>This thesis documents the design, simulation, fabrication, and testing of MEMS variable capacitors (varactors), that are suitable for fabrication using the LIGA process. Variable capacitors can be found in systems such as voltage-controlled oscillators, filters, impedance matching networks and phase shifters. Important figures-of-merit for these devices include quality factor (Q), tuning range, and self-resonant frequency. The simulation results suggest that LIGA-MEMS variable capacitors are capable of high Q performance at upper microwave frequencies. Q-factors as large as 356 with a nickel device layer and 635 with a copper device layer, at operational frequency, have been simulated. The results indicate that self-resonant frequencies as large as 45 GHz are possible, with the ability to select the tuning range depending on the requirements of the application. Selected capacitors were fabricated with a shorter metal height for an initial fabrication attempt. Test results show a Q-factor of 175 and a nominal capacitance of 0.94 pF at 1 GHz. The devices could not be actuated as some seed layer metal remained beneath the cantilevers and further etching is required. As such, LIGA fabrication is shown to be a very promising technology for various dynamically operating microwave MEMS devices.

With experimentation on graphene (an atomic layer of graphite) becoming more and more common it is imperative that we have the capability to shape the material beyond the random manner in which it is deposited by mechanical exfoliation. This capability would be invaluable not only for the interesting electronic and optical properties that can be obtained, but also potentially for characterizing the mechanical resonators that we have been able to fabricate here at Pomona College by suspending few-layer graphene sheets over trenches in SiO2. We propose novel methods for etching graphene that should allow us to shape the material when used in conjunction with our e-beam lithography capabilities.

<p>Couplers are one of the most frequently used passive devices in microwave circuitry. The main function of a coupler is to divide (or combine) a radio frequency signal into (from) two separate signals by a specific ratio and phase difference. With the need for smaller electronic devices, a reduction in the area of a distributed coupler would prove to be valuable. The purpose of this research is to develop, simulate, fabricate and test high aspect ratio microstructure couplers that are smaller in area than existing distributed couplers, and have comparable or better performance. One method used to reduce the area of a distributed coupler is to replace single or multiple transmission lines with lumped element equivalent circuits. One category of lumped elements that has not been extensively implemented is high aspect ratio lumped elements. High aspect ratio lumped elements fabricated with deep X-ray lithography are able to take advantage of using the vertical dimension, and reduce their planar area. In this thesis high aspect ratio lumped elements are used in the design of 3-dB microstructure couplers that show significant area reduction compared to equivalent distributed couplers.</p> <p>The designs of the microstructure couplers were based on the lumped element equivalent circuits of a 3-dB branch-line and a 3-dB rat-race distributed coupler. Simulations were performed to determine the lumped element values that would provide the largest 3-dB bandwidth while still maintaining close to ideal coupling and through values, return loss bandwidth, isolation bandwidth, and phase. These lumped element values were then implemented in the microstructure coupler designs as high aspect ratio microstructure lumped elements. 3-D electromagnetic simulations were performed which verified that the structures behaved electrically as couplers. The microstructure couplers were designed to be 220 &#x00B5;m tall nickel structures with capacitance gap widths of 6 µm.</p> <p>Fabrication of the microstructure couplers using deep X-ray lithography was performed by the microfabrication group at IMT/KIT in Karlsruhe, Germany. Before testing, detailed visual inspection and the etching of the structures was performed at the Canadian Light Source.</p> <p>A total of five microstructure couplers were tested. Four of the tested couplers were based on the 3-dB branch-line coupler, and the fifth coupler was based on the 3-dB rat-race coupler. The microstructure branch-line design that had the best overall results was fabricated on quartz glass substrate and had an operation frequency of 5.3 GHz. The 3-dB bandwidth of the coupler was measured to be better than 75.5% and extrapolated to be 95.0%. At the centre frequency the through and coupled values were -4.32 dB and -4.44 dB. The phase difference between the couplers output ports was designed to be 90.0° and was measured to be 95.8°. The ±5° phase bandwidth was measured to be 12.7% and the isolation bandwidth was 28.8%. The measured results from the other couplers were comparable to simulation results.</p> <p>The main advantage of the microstructure coupler designs over existing distributed couplers is that the microstructure couplers show a significant area reduction. The branch-line microstructure designs were at least 85% smaller in area than their distributed equivalent on quartz glass. The rat-race microstructure design showed an area reduction of 90% when compared to its distributed equivalent on quartz glass.</p>

Microelectromechanical systems (MEMS) devices have been increasing in popularity for radio frequency (RF) and microwave communication systems due to the ability of MEMS devices to improve the performance of these circuits and systems. This interdisciplinary field combines the aspects of lithographic fabrication, mechanics, materials science, and RF/microwave circuit technology to produce moving structures with feature dimensions on the micron scale (micro structures). MEMS technology has been used to improve switches, varactors, and inductors to name a few specific examples. Most MEMS devices have been fabricated using planar micro fabrication techniques that are similar to current IC fabrication techniques. These techniques limit the thickness of individual layers to a few microns, and restrict the structures to have planar and not vertical features. <p> One micro fabrication technology that has not seen much application to microwave MEMS devices is LIGA, a German acronym for X-ray lithography, electroforming, and moulding. LIGA uses X-ray lithography to produce very tall structures (hundreds of microns) with excellent structural quality, and with lateral feature sizes smaller than a micron. These unique properties have led to an increased interest in LIGA for the development of high performance microwave devices, particularily as operating frequencies increase and physical device size decreases. Existing work using LIGA for microwave devices has concentrated on statically operating structures such as transmission lines, filters, and couplers. This research uses these unique fabrication capabilities to develop dynamically operating microwave devices with high frequency performance. <p>This thesis documents the design, simulation, fabrication, and testing of MEMS variable capacitors (varactors), that are suitable for fabrication using the LIGA process. Variable capacitors can be found in systems such as voltage-controlled oscillators, filters, impedance matching networks and phase shifters. Important figures-of-merit for these devices include quality factor (Q), tuning range, and self-resonant frequency. The simulation results suggest that LIGA-MEMS variable capacitors are capable of high Q performance at upper microwave frequencies. Q-factors as large as 356 with a nickel device layer and 635 with a copper device layer, at operational frequency, have been simulated. The results indicate that self-resonant frequencies as large as 45 GHz are possible, with the ability to select the tuning range depending on the requirements of the application. Selected capacitors were fabricated with a shorter metal height for an initial fabrication attempt. Test results show a Q-factor of 175 and a nominal capacitance of 0.94 pF at 1 GHz. The devices could not be actuated as some seed layer metal remained beneath the cantilevers and further etching is required. As such, LIGA fabrication is shown to be a very promising technology for various dynamically operating microwave MEMS devices.

No description available.

Atomic force microscopy is one of the powerful instruments used to explore the mechanical properties of nanoscale materials. It not only can produce high-resolution images and surface mechanical properties, but also can make use of its probe for surface etching. In this study, we first use atomic force microscopy to measure the Adhesion Map of insulin amyloid fibers, then conduct mechanical lithography on the surface with the probe. In the end, we discuss the effect on insulin amyloid fibrils due to exert different forces and different speeds with the probe. According to Nanoindentation theory and Hertzian model, we can derive the Young's modulus of insulin amyloid fibrils from force-indentation relations. Then we cut the Insulin amyloid fibers with probe. The results showed that when we applied 3.23 nN force by the probe, the insulin amyloid fibers began to break. When we applied 7.07 nN force, insulin amyloid fibers are cut off easily. Therefore, we can bite off insulin amyloid fibers of different lengths and sections, and arrange in the desired pattern by atomic force microscope.