No description available.

Wireless Surface Acoustic Wave (SAW) devices were fabricated and tested using planar Lithium Niobate (LiNbO₃) as substrate. The working frequencies were in the 180 MHz and 360 MHz range. Using a network analyser, the devices were interrogated with a wireless range of more than 2 metres. Trials with Electron Beam Lithography (EBL) to fabricate SAW devices working in the 2450 MHz with a calculated feature size of 350 nm are discussed. Charging problems became evident as LiNbO₃ is a strong piezoelectric and pyroelectric material. Various attempts were undertaken to neutralise the charging problems. Further investigation revealed that sputtered Zinc Oxide (ZnO) is a suitable material for attaching SAW devices on irregularly shaped material. DC sputtering was used and several parameters have been optimised to achieve the desired piezoelectric effect. ZnO was sputtered using a magnetron sputtering system with a 75 mm Zn target and a DC sputter power of 250 Watts. Several trials were performed and an optimised material has been prepared under the following conditions: 9 sccm of Oxygen and 6 sccm of Argon were introduced during the process which resulted in a process pressure of 1.2x10⁻² mbar. The coatings have been characterised using Rutherford Backscattering, X-ray diffraction, SEM imaging, and Atomic force microscopy. SAW devices were fabricated and tested on 600 nm thick sputtered ZnO on a Si substrate with a working frequency of 430 MHz. The phase velocity has been calculated as 4300m/s. Non-planar samples have been coated with 500 nm of sputtered ZnO and SAW structures have been fabricated on using EBL. The design frequency is 2450 MHz, with a calculated feature size of 1 µm. The surface roughness however prevented a successful lift-off. AFM imaging confirmed a surface roughness in the order of 20 nm. Ways to improve manufacturability on these samples have been identified.

In this thesis, we demonstrate in-situ scanning electron microscopy techniques for both electron beam lithography (EBL) and in-situ one dimensional nano materials electrical characterization. A precise voltage contrast image positioning for in-situ EBL to integrate nanowires into suspended structures for nanoswitch fabrication has been developed. The in-situ EBL eliminates the stage movement error and field stitching error by preventing any movements of the stage during the nanolithography process; hence, a high precision laser stage and alignment marks on the substrate are not needed, which simplifies the traditional EBL process. The ZnO piezoelectronics is also studied using nano-manipulators in scanning electron microscope. Methods to improve the contact have been demonstrated and the contacts between probe tips and the nanowires are found to have significant impact on the measurement results.

Electron beam lithography (EBL) and Nanoimprint Lithography (NIL) are the promising tools for today’s technology in terms of resolution capability, fidelity and cost of operation. Achieving highest possible resolution is a key concept for EBL where there is a huge request in applications of nanotechnology for sub-20 nm feature sizes. Defining features at these length scales is a challenge, and there is a large demand for resist that is not only capable of giving high resolution but also having low cost and ease of process. In this work I studied Polystyrene (PS) which is an alternative organic e-beam resist in terms of ease of process and resolution capability. I examined the process of electron-beam exposure and attempted to characterize the factors that affect the achieved resolution and sensitivity. Besides this work, I designed and fabricated a new type of mold for NIL since mold fabrication is a key factor for NIL technology. The resolution of NIL process depends on the mold features and polymer mold technology received great attention in terms of cost of fabrication and process, fidelity, and reliability. I used MD 700 Fluoropolymer as a new type of polymer mold which was believed to be a good candidate for the polymer mold of high throughput NIL.

No description available.

Noble metal nanoparticles are of great interest due to their tunable optical and radiative properties. The specific wavelength of light at which the localized surface plasmon resonance occurs is dependent upon the shape, size and composition of the particle as well as the dielectric constant of the host medium. Thus, the optical properties of noble metal nanoparticles can be systematically tuned by altering these specific parameters. The purpose of this thesis is to investigate some of these properties related to metallic nanoparticles. The first several chapters focus on theoretical modeling to predict and explain various plasmonic properties of gold and silver nanoparticles while the later chapters focus on more accurately combining experimental and theoretical methods to explain the plasmonic properties of hollow gold nanoparticles of various shapes. The appendix contains a detailed description of the theoretical methods used throughout the thesis. It is intended to serve as a guide such that a user could carry out the various types of calculations discussed in this thesis simply by reading this appendix.

Electron beam lithography (EBL) and Nanoimprint Lithography (NIL) are the promising tools for today’s technology in terms of resolution capability, fidelity and cost of operation. Achieving highest possible resolution is a key concept for EBL where there is a huge request in applications of nanotechnology for sub-20 nm feature sizes. Defining features at these length scales is a challenge, and there is a large demand for resist that is not only capable of giving high resolution but also having low cost and ease of process. In this work I studied Polystyrene (PS) which is an alternative organic e-beam resist in terms of ease of process and resolution capability. I examined the process of electron-beam exposure and attempted to characterize the factors that affect the achieved resolution and sensitivity. Besides this work, I designed and fabricated a new type of mold for NIL since mold fabrication is a key factor for NIL technology. The resolution of NIL process depends on the mold features and polymer mold technology received great attention in terms of cost of fabrication and process, fidelity, and reliability. I used MD 700 Fluoropolymer as a new type of polymer mold which was believed to be a good candidate for the polymer mold of high throughput NIL.

Microelectronic fabrication of Si typically involves high-temperature or high-energy processes. For instance, wafer fabrication, transistor fabrication, and silicidation are all above 500°C. Contrary to that tradition, we believe low-energy processes constitute a better alternative to enable the industrial application of single-molecule devices based on 2D materials. The present work addresses the postsynthesis processing of graphene at unconventional low temperature, low energy, and low pressure in the poly methyl-methacrylate- (PMMA-) assisted transfer of graphene to oxide wafer, in the electron-beam lithography with PMMA, and in the plasma patterning of graphene with a PMMA ribbon mask. During the exposure to the oxygen plasma, unprotected areas of graphene are converted to graphene oxide. The exposure time required to produce the ribbon patterns on graphene is 2 minutes. We produce graphene ribbon patterns with ∼50 nm width and integrate them into solid state and liquid gated transistor devices. / )e submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract DE-AC02-06CH11357. )e U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the government. Funding text #2 )e Center for Nanoscale Materials was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357. )e authors also acknowledge financial support from Argonne National Laboratory’s Laboratory-Directed Research and Development Strategic Initiative. / Revisión por pares

Oxide materials display a wide range of physical properties. Recently, doped complex oxides have drawn considerable attention for various applications including thermoelectrics. Doped complex oxide materials have high Seebeck coefficients (S) and electrical conductivities (o) comparable to other doped semiconductors but low thermoelectric figure of merit ZT values due to their poor thermal conductivities. For example, niobium doped strontium titanate (SrNbxTi_1-xO₃ or simply Nb:STO) has a power factor comparable to that of bismuth telluride. Semiconductor nanostructures have demonstrated a decrease in thermal conductivity (κ) resulting in an increase in the thermoelectric figure of merit (ZT). Nanostructures of doped oxides like niobium doped strontium titanate, may also lead to decreased κ and a corresponding increase in ZT. The major impediment to nanostructured oxide thermoelectric materials is the lack of suitable fabrication techniques for testing and eventual use. Electron Beam Lithography (EBL) was used to pattern poly-methyl-methacrylate (PMMA) resists on undoped single crystalline SrTiO₃ (STO) substrates which were then filled with Nb:STO using Pulsed Laser Deposition (PLD) at room temperature. This technique produced nanowires and nanodots with critical dimensions below 100 nm, and a yield of approximately 95%. In addition to scanning electron microscopy and atomic force microscopy morphological studies of the patterned oxide, thin film analogues were used to study composition, crystallinity and electrical conductivity of the material in response to a post deposition heat treatment. Since the thin films were grown under similar experimental parameters as the oxide nanostructres, the patterned oxides are believed to be stoichiometric and highly crystalline. The study found that using a combination of EBL and PLD, it is possible to produce highly crystalline, doped complex oxide nanostructures with excellent control over morphology. Furthermore, the technique is applicable to nearly all materials and provides the capability of patterning doped oxide materials without the requirement of etching or multiple lithography steps makes this approach especially interesting for future fundamental materials research and novel device fabrication. / Master of Science

This thesis covers nanofabrication of central stops for application in soft X-ray imaging using electron-beam lithography for pattern definition. Central stops are small scale optical components used in combination with an order sorting aperture to eliminate the higher order and zeroth order of light after diffraction from a Fresnel zone plate. The main objectives of this study were to produce central stops with the desired parameters and to obtain an understanding of the nanofabrication process. A challenge which was encountered during the fabrication of the central stops was uncertainties in electroplating time, resulting in multiple plating rounds and in turn impacting the quality of the nanostructures. Another challenge which presented itself was that the structures disappeared on the chip with an uneven resist layer, suggesting that the resist layer’s smoothness is important. A key consideration when fabricating structures on this small scale is therefore to ensure the smoothness of the resist layer. Despite these challenges, one chip was successfully fabricated and could likely be used in the optical system for the SoftiMAX beamline, a beamline used for X-ray imaging at MAX IV, a fourth generation synchrotron radiation facility in Lund. In summary, recommendations for future replications and research would be to use chips with evenly coated resist, to make sure to only electroplate once and, if working with similar structures and parameters, to electroplate for a longer time than calculations suggest.