Indium Tin Oxide film characterization using the classical Hall effect

We have used the classical Hall effect to electrically characterize Indium Tin Oxide (ITO) films grown by two different techniques on silica substrates. ITO films have the unique property that they can be both electrically conducting (and to be used for a gate electrode for example) as well as optically transparent (at least in the visible part of the spectrum). In the near infrared (NIR) the transmission typically reduces. However, the light absorption can in principle be compensated by growing thinner films.Comment: 2 pages Optoelectronic and Microelectronic Materials & Devices (COMMAD), 2014 Conferenc

Plasmonics-enabled semiconductor photodetectors

© 2017 Dr. Evgeniy PanchenkoThe ever increasing demand for high-speed data processing requires faster operation of computer processors and peripherals. Despite the continual improvement in semiconductor technology processes which, in turn, leads to corresponding increases in logic gate switching frequency, the speed of the modern central processing units remains relatively constant. This speed limitation is primarily determined by metallic interconnects in the integrated circuits. Numerous enhancements have been introduced to conventional CMOS technology in order to decrease the resistance and capacitance of the interconnects. Even though these changes have markedly improved the characteristics of interconnects, further developments of this technology are extremely challenging and cost-ineffective. Therefore, as the current technology is rapidly reaching its limits, a new approach is required to overcome the existing issues and build high-speed digital devices. Recent advances in the understanding of surface plasmon polaritons open up an opportunity to overcome this limitation and greatly increase the operating speed of future digital integrated circuits. Despite the exceptional properties of surface plasmons this task is challenging as it requires the optical components to be compatible with current planar technology. The main aim of this work is to progress research into the development of a technology which will permit overcoming current issues limiting increases in processor operation speed such as the RC parameters of metallic interconnects. In this thesis comprehensive analytical and numerical studies of a plasmonic input port, waveguide and modulator will be presented. Excitation of surface plasmons as well as their propagation along the waveguide will be experimentally demonstrated. It will be shown that waveguide-coupled metal-semiconductor-metal photodetectors enable an in-plane detection of the surface plasmons - an important property required for successful integration into modern semiconductor technology. The design presented here, therefore, could underpin a new class of optoelectronic devices that enable the integration of surface plasmons as signal carriers in future high-speed optoelectronic processors. The potential applications of surface plasmons are not limited to high-speed interconnects. The utilisation of the phenomenon of localised surface plasmons establishes an opportunity to create 2D materials with a tailored electromagnetic response. The second aim of this work, therefore, is to develop a technology which can improve the existing properties or add functionality to conventional photodetectors. This thesis focuses on a demonstration of planar polarisation-sensitive detectors and colour camera pixels. Plasmonic metasurfaces can be used to tailor the sensitivity of photodetectors to potentially arbitrary states of polarisation or wavelength of the incident beam. In this thesis a novel design for a polarisation-sensitive differential photodetector is presented. It will be experimentally demonstrated that such a photodetector exhibits a high robustness to intensity fluctuations which is a highly desirable property for telecommunication applications as well as being able to discriminate between different polarisation states. Furthermore, it is shown that plasmonic metasurfaces can also be used as integrated colour filters in camera pixels, permitting a fully planar design and eliminating the cross-talk issue associated with conventional pixels

Analyzing the causes for the dispersion of the fast reactor spent fuel rod cladding properties

The swelling, corrosion and high-temperature embrittlement behavior of the fast-neutron sodium-cooled reactor standard and test fuel rod claddings was studied following the operation up to a damaging dose of 55 to 69 dpa. The tested characteristics were found to differ sensitively in conditions similar to irradiation for the claddings of the experimental tube conversion technology. Unlike the standard fuel rod claddings, the test rod claddings were additionally heated in the process of fabrication to homogenize the solid solution at different temperatures and austenitization times. On the whole, this led to an increased cladding resistance contrary the damaging factor of the reactor environment. The positive effect is explained by the influence of carbon and the morphology of swelling-reducing alloying elements, as well as by the nature of the carbide and intermetallide phase precipitation. However, the dispersion of the post-irradiation properties which remained significant and was also earlier observed in the standard rods is explained by potential differences in the heat treatment technology and the irradiation temperature in conditions of a hard-to-control coolant flow velocity. The swelling rate and the in-fuel corrosion depth for the test technology tubes were respectively 0.04 to 0.058%/dpa and 20 to 47 μm; similar values for the test material are 0.036 to 0.056%/dpa and 15 to 35 μm respectively. The short-term mechanical properties of the test fuel rods at a temperature of 600 °C showed a smaller tendency towards high-temperature embrittlement. The dispersion of the properties was caused by the chemical and structural heterogeneity as the result of the tube fabrication

Plasmonic Metasurface-Enabled Differential Photodetectors for Broadband Optical Polarization Characterization

The polarization state of an optical field is central to applications in optical communications, imaging, and data storage as well as furthering our understanding of biological and physical systems. Here we demonstrate two silicon photodetectors integrated with aluminum nanoantennas capable of distinguishing orthogonal states of either linearly or circularly polarized light with no additional filters. The localized plasmon resonances of the antennas lead to selective screening of the underlying silicon from light with a particular polarization state. The planar device, fully compatible with conventional CMOS fabrication methods, incorporates antennas sensitive to orthogonal states of polarization into two back-to-back Schottky photodetectors to produce a differential electrical signal that changes sign as the polarization of an incident optical beam changes from one basis state to the orthogonal state. The non-null response of the devices to each of the basis states expands the potential utility of the photodetectors while improving precision. Each device is wrapped into a spiral footprint to provide compatibility with the circular profile of conventional optical beams and has an overall diameter of 50 μm. The sensitivity of these devices is demonstrated experimentally over a wavelength range from 500 to 800 nm, establishing their potential for integration into a wide range of optical systems