abstract: Solar energy has become one of the most popular renewable energy in human’s life because of its abundance and environment friendliness. To achieve high solar energy conversion efficiency, it usually requires surfaces to absorb selectivity within one spectral range of interest and reflect strongly over the rest of the spectrum. An economic method is always desired to fabricate spectrally selective surfaces with improved energy conversion efficiency. Colloidal lithography is a recently emerged way of nanofabrication, which has advantages of low-cost and easy operation. In this thesis, aluminum metasurface structures are proposed based on colloidal lithography method. High Frequency Structure Simulator is used to numerically study optical properties and design the aluminum metasurfaces with selective absorption. Simulation results show that proposed aluminum metasurface structure on aluminum oxide thin film and aluminum substrate has a major reflectance dip, whose wavelength is tunable within the near-infrared and visible spectrum with metasurface size. As the metasurface is opaque due to aluminum film, it indicates strong wavelength-selective optical absorption, which is due to the magnetic resonance between the top metasurface and bottom Al film within the aluminum oxide layer. The proposed sample is fabricated based on colloidal lithography method. Monolayer polystyrene particles of 500 nm are successfully prepared and transferred onto silicon substrate. Scanning electron microscope is used to check the surface topography. Aluminum thin film with 20-nm or 50-nm thickness is then deposited on the sample. After monolayer particles are removed, optical properties of samples are measured by micro-scale optical reflectance and transmittance microscope. Measured and simulated reflectance of these samples do not have frequency selective properties and is not sensitive to defects. The next step is to fabricate the Al metasurface on Al_2 O_3 and Al films to experimentally demonstrate the selective absorption predicted from the numerical simulation. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2019

No description available.

Malongen consists of two volumes containing housing, a gallery, and a restaurant. The design language of the base comes from a 3D scan of the rock 30 meters north of the plot. The buildings are a design interaction to explore the tension between the historical mountain cut and a design interaction. With a digital imitation of the rock the buildings intend to mimic the surrounding area. The rock, that is the historical imprint of the place, is now translated into buildingelements, as a result of my manipulation of the file. This project has investigated how we can create a contemporary buidling that refer to a historical site and keep telling a story about time.

Research on heterojunction (HJ) metal oxide thin film transistors (TFTs) has accelerated remarkably over the last decade due to their superior performance over their conventional single-layer (SL) counterparts. Promising results in laboratory-scale demonstrations have further triggered an increased number of investigations into fabrication and processing techniques for the large-scale integration of HJ metal oxide TFTs. Nevertheless, a lack of consensus regarding the most appropriate scalable manufacturing technique, which combines low-cost and high-throughput fabrication, holds back new opportunities for HJ metal oxide TFTs in emerging applications. In this thesis, novel approaches and strategies are introduced to facilitate the large-scale integration of HJ metal oxide TFTs. The first study of this dissertation introduces the solution-processed In2O3/ZnO heterojunction TFTs with a high-κ bilayer dielectric consisting of Al2O3/ZrO2. Processing was carried out on rigid glass as well as flexible PEN substrates via rapid flash lamp annealing (FLA) as an alternative scalable and high-throughput processing route to conventional thermal annealing. In the second study of the dissertation, a novel 3D/2D/3D mixed-dimensional channel concept was developed with the combination of scalable spray coating and FLA techniques. The insertion of sprayed MoS2 nanoflakes between flashed SnO2/ZnO HJ results in outstanding device performance with a high mobility value of 62 cm2/Vs compared to single layers as well as heterojunction metal oxide TFTs, showing maximum mobility of 4.48 cm2/Vs. In the third study, the fabrication of In2O3/ZnO heterojunction metal oxide TFTs with solution-processed conductive Ti3C2Tx MXene contacts using a processing route that fully relies on a scalable spray coating process is demonstrated as an alternative to low-throughput vacuum-based electrodes. Notably, the proposed approach was successfully upscaled to a 4-inch glass substrate, underlining the significant potential garnered by MXene electrodes for industrial-scale electronics. The last study of the dissertation exploits the advantages of the adhesion-lithography (a-Lith) technique, which enables the development of coplanar self-aligned gate (SAG) In2O3/ZnO heterojunction TFTs and their facile integration into large-area electronics. Using the a-Lith technique, coplanar SAG architectures were fabricated where the gate and dielectric (Al and Al2O3, respectively) are located side by side with the source/drain electrodes (Au), separated from each other by nanogaps.

Antenna-coupled detectors provide uncooled, cost-effective solutions for infrared and millimeter-wave imaging. This work describes the design, fabrication, measurement, and optimization of several types of antenna-coupled detectors for LWIR (8 - 12 µm) and 94 GHz radiation. Two types of millimeter-wave antenna-coupled detectors were fabricated and tested: a slot antenna coupled to a bolometer, and a patch antenna coupled to a SiC Schottky diode. Electromagnetic modeling of the antennas helped guide the design of antennas with better impedance matching to the detectors. Schottky diodes are discussed as detectors for millimeter-wave and infrared radiation, with the goal of increasing the cutoff frequency to allow infrared detection. The magnitude of response of antenna-coupled bolometric detectors to infrared radiation is affected by the thermal-conduction properties of the sensor structure. Two fabrication processes were developed to improve the thermal isolation of the antenna-coupled bolometer from its substrate. The first process creates a membrane beneath the device. Measured results show a factor of 100 increase in responsivity over an identical device without a membrane. The second process thermally isolates the device from its substrate by suspending the metallic structure in air. Several factors for optimization of infrared antenna-coupled detectors are investigated. The complex dielectric function of the metal from which the antenna is constructed can affect the performance of the device. The use of a ground plane and dielectric standoff layer beneath the antenna can increase the sensor responsivity. Dielectric material properties and thicknesses are considered, and incorporated in device simulations. Finally, a potential fabrication process is presented for via connections from the antenna-coupled detector through a ground plane to bond pads to mitigate the effect of bias lines on antenna behavior.

In the area of MEMS there exists a tremendous need for communication between the micro-device and the macro world. A standard protocol or at least multiple standards would be of great use. Electrical connections have been standardized for many uses and configurations by the integrated circuit industry. Standardization in the IC industry has created a marketplace for digital devices unprecedented. In addition to the number of "off the shelf" products available, there exists the possibility for consumers to mix and match many devices from many different manufacturers. This research proposes some similar solutions as those for integrated circuits for fluid connections and mechanical configurations that could be used on many different devices. In conjunction with offering the capability to facilitate communication between the micro and macro worlds, the packaging solutions should be easy to fabricate. Many devices are by nature non-standard, unique, designs that make a general solution difficult. At the same time, the micro-devices themselves will inevitably need to evolve some standardization. In BioMEMS devices the packaging issue is concerned with delivering a sample to the device, conducting the sample to the sensor or sensors, and removing the sample. Conducting the sample to the sensor or sensors is usually done with microchannels created by standard MEMS fabrication techniques. Many current designs then utilize conventional machining techniques to create the inlet and outlet for the sample. This work proposes a rapid prototyping method for creating the microchannel and inlet / outlet in simplified steps. The packages developed from this process proved to be an effective solution for many applications.

For the past decade, the epoxy based photoresist SU-8 has been used commercially and in the lab for fabricating micro- and nano-structures. Investigators have studied how processing parameters such as pre- and post-exposure bake temperatures affect the resolution and quality of SU-8 structures patterned using ultraviolet or x-ray lithography. Despite the advances in understanding the phenomena, not all of them have been explored, especially those that are specific to multi-photon direct laser writing (mpDLW). Unlike conventional exposure techniques, mpDLW is an inherently three-dimensional (3D) process that is activated by nonlinear absorption of light. This dissertation reports how several key processing parameters affect mpDLW using SU-8 including pre-exposure bake duration, focal depth, incident laser power, focal-point scan speed, and excitation wavelength. An examination of solvent content of films at various stages in the mpDLW by 1H-NMR shows that even moderate solvent content (over 1 wt-%) affects film viscosity and photoacid diffusion lengths, and can greatly affect the overall fidelity of small features. A study of micro-fabricated feature size versus writing depth in the material shows that even slight refractive index mismatch between SU-8 and the medium between it and the focusing objective introduces spherical aberration that distorts the focus, causing feature size to decrease or even increase in size with writing depth, depending on the average exposure power used. Proper adjustment of the average exposure power was demonstrated as a means to fabricate more uniform features with writing depth. Third, when varying the power and scan speed, it was observed that the feature-size scales with these two parameters in a manner that is consistent with a three-photon absorption mechanism at an excitation wavelength of 800 nm. When an iii excitation wavelength of 725 nm is used, the feature-size scaling becomes consistent with that of two photon absorption. This shows that the photoinitiators in the SU-8 can be activated by either two- or three-photon absorption over this wavelength range. Using an irradiance of ~2 TW cm-2 and elongated femtosecond pulses resulted in an observed fourth order power dependence. This observation is in agreement with the literature and suggests that the effective absorptive nonlinearity is also sensitive to pulse duration. These findings will be useful for creating accurate models of the process of mpDLW in SU-8. These models could be used to optimize the processing parameters and develop new processing methods and materials for high-resolution fabrication of robust 3D microstructures. Some of the findings were used to develop a method for fabricating functional microlenses on the tip of optical fibers. This approach opens a new route to functional integrated photonic devices.

Given the current social and business trends with digital fabrication and communication technologies, change in the manner and means of physical object production is clearly on the horizon. Recent peripheral projects show how access to digital fabrication and communication tools pull information for making toward the user, and enable the distribution of information and product outward. They also demonstrate vibrant user innovation in smaller scale projects for both personal and commercial applications. These current trends and peripheral projects are used to help locate where design and designers may find areas of growth in a potentially less-centralized, and more varied landscape of product development and production in the future. / Master of Science

Yes / In recent years 3D printing has gained popularity amongst industry professionals and hobbyists alike, with many new types of Fused Filament Fabrication (FFF) apparatus types becoming available on the market. A massively overlooked component of FFF is the requirement for a simple method to calculate the geometries of polymer depositions extruded during the FFF process. Manufacturers have so far achieved adequate methods to calculate tool-paths through so called slicer software packages which calculate the required velocities of extrusion from prior knowledge and data. Presented here is a method for obtaining a series of equations for predicting height, width and cross-sectional area values for given processing parameters within the FFF process for initial laydown on to a glass surface.

<p> LiYO2 is a lithium ion conductor stable to pure lithium metal. The goal of the present work was to design and construct an electrochemical cell and demonstrate the use of LiYO2 as an electrolyte since this has never been previously done. The electrolyte was fabricated by slip casting in powder molds. A Y2O3-MgO composition was identified and used to fabricate a lid for the cell. Impervious cells were obtained by liquid phase joining and sintering techniques. Heating rate was found to be a key parameter in the success of this procedure. The cell was evaluated in terms of stability as a sensor and chemical pump by measuring EMF for two different Li-Zn alloys between 250 and 600°C. The configuration was as follows: (RE) (-) Ta Li,Sn | LiYO2 | Li,Zn Ta (+) (WE)</p> <p> The cell showed no significant attack after 40 days working with pure lithium. Stability and reproducibility of EMF values was obtained for the concentrations of Li studied. Solidus and liquidus temperatures were determined for the 5 and 10 mol% Li compositions in good agreement with published phase diagrams. Variations of EMF with respect to temperature or concentration followed the expected thermodynamic relationships. Results indicate that the LiYO2 electrolyte cell could be useful in assessment of the thermodynamics of lithium alloys.</p> / Thesis / Master of Engineering (MEngr)