Controlled Deposition of Tin Oxide and Silver Nanoparticles Using Microcontact Printing

This report describes extensive studies of deposition processes involving tin oxide (SnOx) nanoparticles on smooth glass surfaces. We demonstrate the use of smooth films of these nanoparticles as a platform for spatially-selective electroless deposition of silver by soft lithographic stamping. The edge and height roughness of the depositing metallic films are 100 nm and 20 nm, respectively, controlled by the intrinsic size of the nanoparticles. Mixtures of alcohols as capping agents provide further control over the size and shape of nanoparticles clusters. The distribution of cluster heights obtained by atomic force microscopy (AFM) is modeled through a modified heterogeneous nucleation theory as well as Oswald ripening. The thermodynamic modeling of the wetting properties of nanoparticles aggregates provides insight into their mechanism of formation and how their properties might be further exploited in wide-ranging applications

Fabrication Of Two-Dimensional Nanostructures On Glass Using Nanosphere Lithography

It is desired to have artificial optical materials with controllable optical properties. Optical glass is the most common optical material for various applications. This research will attempt to create a thin layer on the substrate with controllable optical properties. The thin layer is a composite material with nanoscale features and controllable refractive index. Two-dimensional (2D) nanostructures will be created on the surface of optical glass using nanosphere lithography. In comparison with conventional techniques, this approach is more efficient and cost-effective for the creation of large areas of thin surface layers as an artificial material. A uniform monolayer of nanospheres will be deposited on soda-lime glass slides. Deposition will be performed via a slide-coating technique to take advantage of capillary forces. The slides will be etched with vapor-phase hydrofluoric acid (HF) to create 2D structures. Vapor-phase etching is selected in order to etch the substrate without disturbing the monolayer nanoparticle mask. The etching rate of nanostructures will be studied. An atomic force microscope (AFM) is to be used to monitor the nanosphere monolayers and etching analysis. The resultant thin-layer of modified substrate serves as an artificial material with a desired refractive index which modifies the surface reflection and transmission properties. The effective refractive index of the artificial layer is smaller than the refractive index of the substrate and can be varied by changing the size of the nanoparticles and depth of etching. It is expected that the substrate with the created artificial material layer demonstrates reduced reflectivity in optical wavelengths

Development of in-situ techniques for predicting PEB temperature

Master'sMASTER OF ENGINEERIN

Scanning Probe Alloying Nanolithography (SPAN)

In recent years, nanowires have become increasingly important due to their unique properties and applications. Thus, processes in the fabrication to nanostructures has come a focal point in research. In this research, a new method to fabricate nanowires has been developed. The new technique is called the Scanning Probe Alloying Nanolithography (SPAN). The SPAN was processed using an Atomic Force Microscope (AFM) in ambient environment. Firstly, an AFM probe was coated with gold (Au), and then slid on a silicon (Si) substrate. The contact-sliding motion generated a nanostructure on the substrate, instead of wear. Subsequently, careful examination was carried out at the scale relevant to an AFM probe, in terms of physical dimension and electrical conductivity. The measured conductivity value of the generated microstructures was found to be between the conductivity values of pure silicon and gold. Simple analysis indicated that the microstructures were formed due to frictional energy dispersed in the interface forming a bond to sustain mechanical wear. This research proves the feasibilities of tip-based nanomanufacturing. The SPAN process was developed to increase efficiency of the technique. This study also explored the possibility of the applications as a biosensor and a flexible device. This dissertation contains nine sections. The first section introduces backgrounds necessary to understand the subject matter. It reviews current status of the nanofabrication technologies. The basic concepts of AFM are also provided. The second section discusses the motivation and goals in detail. The third section covers the new technology, scanning probe alloying nanolithography (SPAN) to fabricate nanostructures. The fourth talks about characterization of nanostructures. Subsequently, the characterized nanostructures and their mechanical, chemical, and electrical properties are discussed in the fifth section. In the sixth section, the new process to form a nanostructure is evaluated and its mechanism is discussed. The seventh section discusses the feasibility of the nanostructures to be used in biosensors and flexible devices. The conclusion of the research is summarized in the seventh section

Development of Si/SiGe technology for microwave integrated circuits

A complete fabrication process has been developed for the realisation of Si/SiGe microwave integrated circuits (SIMICs). Using the process, a number of active and passive elements for microwave circuits have been demonstrated including 1. Metal gate p-SiGe MOSFETs . 2. Low loss transmission lines on CMOS grade silicon. 3. High quality spiral inductors on CMOS grade silicon. 4. High performance metal gate strained silicon n-MOSFETs. Single stage amplifiers have been designed based on the technology developed in this work. The MOSFETs have good DC performance. Strained SiGe p-channel MOSFETs with 1 mum gate length have an extrinsic transconductance of 36 mS/mm. Strained silicon n-channel MOSFETs with 0.3 mum gate length have extrinsic transconductance of 230 mS/mm. The RF performance of a metal gate 0.3 mum gate length strained silicon MOSFET is measured, with cut off frequency and maximum frequency of oscillation of 20 GHz and 21 GHz respectively. Coplanar waveguide transmission lines of 50 Ohm characteristic impedance, fabricated using spin on dielectrics on a CMOS grade silicon subsfrate, have losses less than 0.5 dB/mm up to 60 GHz. Spiral inductors fabricated on the low loss dielectric have Q > 15. Using the passive and active element library developed, single stage amplifiers were designed with gain of 12 dB at 3 GHz or 7.5 dB at 6 GHz. The device layer structures were designed using a simple ID Poisson solver. The p-channel device used a concentration graded SiGe channel to obtain high mobility and carrier concentration. The n-channel RF device with a strained silicon channel incorporates a metal gate technology that is'directly responsible for the high values of f achieved. The spiral inductors and coplanar waveguides are fabricated using a spin on dielectric process to separate them from the lossy silicon substrate. The same technology is used to reduce the parasitic capacitance of device contact pads. The engineering conclusion of this work is that SIMICs, for applications in the frequency range 1 to 10 GHz, can be made with the current passive and active element library at the University of Glasgow. Further improvement in both passive and active element performance to increase the frequency is set out in future work. From a practical viewpoint a process is now in place that will underpin the University of Glasgow's Si / SiGe SIMIC projects in the future

A micro-fabricação aplicada ao processo de micro-injecção

Dissertação de Mestrado em Projecto e Fabrico de MoldesA miniaturização de componentes e sistemas incorporados nos mais diversos ramos de indústria, aplicações médicas e domésticas tem vindo a ser uma realidade nas duas últimas décadas. A evolução constante de técnicas de micro-fabricação e de materiais tem criado novas aplicações, mais complexas, mais eficazes e mais ambiciosas no que toca à visão do futuro. A massificação destes mini, micro e nanosistemas depende fortemente da capacidade de replicação dos seus componentes. Esta tese de Mestrado discute a aplicabilidade das técnicas de micro-fabricação existentes actualmente aos processos de micro-replicação. Com esse objectivo presente, é feita uma análise ao estado da arte dos processos de micro-fabricação e a sua classificação quanto à sua aptidão de produzirem directamente ferramentas para replicação. Uma vez seleccionado um componente para os testes de produção em série, são avaliadas as suas necessidades e escolhido um processo de micro-fabricação, sendo este utilizado para produzir uma ferramenta para o processo de micro-injecção. As limitações técnicas que alguns processos de micro-fabricação possuem actualmente justificam a necessidade de uma análise comparativa entre aquilo que é possível realizar e o seu custo, de modo a privilegiar a componente produtiva do processo.The miniaturisation of components and systems integrated into many types of industries, medical and domestic applications has become a reality in the last two decades. The constant evolution of micro-fabrication techniques and materials has been creating new fields of applications, more complex, more effective and more ambitious in which concerns to a vision of the future. The massification of these mini, micro and nanosystems strongly depends on the capacity of replicating their components. This Master thesis discusses the applicability of the existing micro-fabrication techniques to replication processes. With that objective in mind, an analysis is made to the state-of-the-art micro-fabrication processes and these are classified on their ability to directly produce tools for replication. Then, once selected a component for replication tests, its technical needs are evaluated and a micro-fabrication process is chosen and afterwards, used to produce a tool for the micro-injection process. The technical limitations that some micro-fabrication processes possess nowadays justify the need for a comparison between what is possible to accomplish and its cost, so the productive component of the process can be privileged