Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006. / Includes bibliographical references (p. 63-65). / High-energy-density lithium ion batteries have enabled a myriad of small consumer-electronics applications. Batteries for these applications most often employ a liquid electrolyte system. However, liquid electrolytes do not allow for small scale and thin-film production as they require hermetic sealing. The aim for batteries in any size or shape, without the restrictions liquid components pose, has led to the development of solid electrolyte systems. ll-solid-state thin-film batteries add a new dimension to the space of battery applications. The purpose of this thesis is to assess the application potential for solid-state thin-film batteries, particularly with regard to CMOS integration. Such batteries were developed with the aim of creating a power unit on a silicon microchip. The various degrees of integration of thin-film batteries on a silicon wafer are examined. All of them show limitations that make fabrication of batteries on a wafer not viable at present from a business standpoint. A search for other commercializable applications for thin-film batteries leads to solid-state bulk batteries made from thin-film batteries. The underlying technology here as well as the market situation and a potential business model are discussed. / by Julia Greiner. / M.Eng.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1995. / Includes bibliographical references (leaves 122-123). / by Andrew Chinshun Chen. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1988. / Includes bibliographical references. / by Barbara Ann Masi. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2002. / Includes bibliographical references (p. 111). / Damping in MEMS resonators was studied experimentally and numerically. Quality factor measurements were performed on Draper gyroscopes made from boron doped silicon wafers with varying amount of germanium (0%, 2%, 23%, 30% ). The quality factors of gyroscopes with germanium were measured to be lower than those without germanium, due to increased anelastic damping. Specifically, the decreased thermal conductivity in the devices with germanium causes those devices to experience thermoelastic damping of a greater magnitude than the germanium-free devices. The amount of damping exhibited is found to be well explained by existing analytical expressions for thermoelastic dissipation in a beam model. The governing equations of thermo elasticity dictate that the amount of damping that a resonator undergoes is a function of both material properties as well as device geometry. Damping will become greatest at operating cycle times that are of the same scale as the thermal relaxation times of the device material. Due to the fact that analytical expressions exist for only a few simple geometries, a finite element model was developed to evaluate thermoelastic damping in more complicated geometries. The finite element model is demonstrated to be in good qualitative agreement with the analytical expressions, and is used to analyze the impact of design modifications such as the addition of fillets and anchors to a simple beam model. It is shown that depending on the size scale of the resonator (which dictates the amount of internal damping), these geometric modifications may either hinder or improve resonator damping characteristics. / by John P. Gorman. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1997. / Includes bibliographical references (leaves 106-109). / Ling Liao. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1989. / Includes bibliographical references (leaf 26). / by Ambuj Daya Sagar. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1985. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Bibliography: leaves 123-129. / by Barbara Poggiali. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2009. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 202-211). / The rapid growing needs for high data transmission bandwidth challenge the metal interconnection technology in every area from chip-level interconnects to long distance communication. Silicon photonics is an ideal platform for the implementation of optical interconnection capable of high bandwidth and low power consumption by integrating electronic and photonic devices on silicon. Many optical components in silicon photonics have been extensively studied, among which a silicon-based laser is arguably the most challenging element. This thesis mainly focuses on using engineered germanium as the optically active material for silicon-based light emitters with many potential benefits: Si-CMOS compatibility (both material and processing), electrical injection capability, and direct gap emission at technologically important 1.55 pm telecommunication band. Tensile-strained n+ germanium is capable of behaving like a direct band gap material owing to the direct band gap shrinkage upon tensile strain and the state-filling in the indirect L valleys with extrinsic electrons from n-type dopants. Our theoretical calculation using a direct band-to-band transition model has shown great benefit of tensile strain and n-type doping on the direct gap optical gain characteristics. By considering free carrier absorption which dominates the optical loss we have proven net gain can be achieved in 0.25% tensile-strained Ge with n-type doping concentration in a range of 1019 to mid-1020 cm-3. The injection threshold of the net gain is about 1018 cm-3 which can readily be achieved with either optical pumping or electrical pumping. / (cont.) The net gain is in favor of the raise of temperature in a large injection range (threshold to mid-1019 cm-3) because of the increased number of high energy electrons in the direct F valley contributing to the direct band-to-band radiative recombination. We have successfully grown single crystalline germanium epitaxially on silicon with a two-step approach. Tensile strain between 0.2% and 0.25% is formed in germanium upon cooling from high growth temperature (or post-growth annealing temperature) to room temperature because of the larger thermal expansion coefficient of germanium compared to that of silicon. Phosphorus are in situ doped in germanium as n-type dopants during the epitaxial growth. By carefully adjusting the growth condition, we have obtained active doping concentration as high as 2 x 1019 cm-3. An in situ doping model built by considering the transportation processes and the reactions of phosphorus-containing species well explains the temperature dependence of the doping concentration. The deviation from the model while analyzing the influence of other growth parameters indicates possible compensation of the dopants. We used photoluminescence (PL) measurement to study to the optical properties of tensile-strained n+ germanium. Room temperature PL was observed from the epitaxial Geon-Si films near the direct gap wavelength of 1600nm. The direct gap PL spectrum exhibits Ge direct band-to-band optical transition properties. The direct gap PL intensity increases with n-type doping concentration as a result of the indirect valley state filling effect which increases the Fermi level leading to higher excited electron density in the direct F valley. / (cont.) The direct gap PL intensity also increases with temperature because of the increased number of high energy direct F valley electrons thermally activated from the indirect L valleys. This effect make germanium light emission robust to inevitable heating effects during operation in practice. The "unusual" n-type doping and temperature dependences of PL are unique properties of the direct gap emission from indirect bandgap Ge. There effects are predicted by our theory, and the observation of these effect in experiments is a strong evidence of validity of the theory. In order to study the electrical injection in Ge, we fabricated Si/Ge/Si heterojunction light emitting diodes (LEDs). Room temperature direct gap electroluminescence (EL) are observed from these diodes. It is the first observation of EL from Ge. The direct gap EL spectrum matches the PL spectrum underlying the same injection mechanism in both electrical pumping and optical pumping. The direct gap EL intensity increases superlinearly with injection current because of the raised quasi Fermi level leading to the increased fraction of the injected electrons in the direct F valley. The internal quantum efficiency of the LEDs is on the order of 10-3 consistent with the finite-element simulation results. This EL efficiency can be improved to 10-1 if doping germanium active region with n-type. The design of n+Ge based heterojunction diodes has been simulated, and an optimal design has been proposed based on the simulation. We used pump-probe spectroscopy to measure material gain of the tensile-strained n+ germanium. / (cont.) We have observed an optical bleaching effect, the reduction of absorption under pumping and the prelude of optical gain, above the direct band gap energy from the engineered Ge. The population inversion factor increases with the n-type doping concentration in Ge, as predicted by the theory. By increasing the injection level using a Ge micro-mesa structure carrier confinement, we have successfully demonstrated the net gain, i.e. population inversion. A peak gain of 50 ± 25 cm-1 at 1605 nm has been obtained from the experiment. It is the first report of observing net gain from germanium. / by Xiaochen Sun. / Ph.D.

Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2011. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 59-60). / In nature, aquatic birds can interact with water without their feathers being easily wetted; some species dive tens of meters and emerge to spread their wings to dry. In past studies attempting to connect such ecological behavior and feather structure, the typical approach of microscopy has demonstrated the difficulty in characterizing specimens as delicate and complex as feathers by visual techniques alone. In this work, the question was addressed of how various species balance the wettability problem with the need to dive to various depths or to remain on or near the water surface as dictated by their feeding habits. Texture of wing feathers from six different species of aquatic birds was characterized by measuring contact angles and applying the previously developed framework of the effective spacing ratio, D*, and robustness factor, A*, according to the Cassie-Baxter relation for composite interfaces. This "effective microscopy" technique was successfully employed to assess the wettability and robustness of bird feather textures. The observable water-related behaviors of diving, wing-spreading, shallow foraging, and dabbling for the species studied were explained as partly determined by feather structure, exhibiting effective- D* analysis as an adequate technique for characterizing complex, textured surfaces, fabricated or natural. / by Jesus O. Guardado. / S.B.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2009. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 79-81). / Flash memory, the current leading technology for non-volatile memory (NVM), is projected by many to run obsolete in the face of future miniaturization trend in the semiconductor devices due to some of its technical limitations. Several different technologies have been developed in attempt for replacing Flash memory as the most dominant NVM technology; none of which seems to indicate significant success at the moment. Among these technologies is RRAM (Resistive Random Access Memory), a novel type of memory technology which has only recently emerged to join the race. The underlying principle of an RRAM device is based on the colossal electroresistance (CER) effect, i.e. the resistance switching behavior upon application of voltage of varying polarity and/or magnitude. This thesis aims to investigate the CER effect and how it can be designed to be a non-volatile memory as well as other novel application, e.g. memristor. The various technical aspects pertaining to this phenomenon, including the materials and the physical basis, are explored and analyzed. As a complementary to that, the market potential of the RRAM technology is also assessed. This includes the market study of memory industry, the current intellectual property (IP) landscape and some of the relevant business strategies. The production strategy (i.e. the production cost, initial investment, and pricing strategy) is then derived from the technical and market analysis evaluated earlier and with using some reasonable assumptions. / by Aulia Tegar Wicaksono. / M.Eng.