Semiconductor and Optical Materials Commons^™

Optimization Of Pulse Plating Additives And Plating Parameters For High Aspect Ratio Through Holes, Kai Yang, Ji-Da Chen, Shi-Jin Chen, Wei-Lian Xu, Mao-Gui Guo, Jin-Chao Liao, Zeng-Kun Wu

Journal of Electrochemistry

As an important component in electronic products, printed circuit board (PCB) plays a supporting and interconnecting role for the electronic components in it. With the development of communication technology, electronic products are developing in the direction of “thin, light and small”, and high density interconnection (HDI) comes into being. Due to the high-density interconnection characteristics of HDI boards, the thickness of the board is increasing. At the same time, in order to reserve space for the laying of fine lines on the subsequent board surface, the diameter of the through holes on the board is also decreasing, so the depth-diameter …

Research Progresses Of Cobalt Interconnect And Superfilling By Electroplating In Chips, Li-Jun Wei, Zi-Han Zhou, Yun-Wen Wu, Ming Li, Su Wang

Journal of Electrochemistry

Copper interconnect using dual damascene technology has always been the main means for metallization in the back end of line process. However, with the size effect becoming more and more obvious due to feature size reduction, copper interconnect can no longer meet the demand for high circuit speed in Post-Moore era. Following copper interconnection, cobalt interconnection in chips attracts much attention as an interconnect technology by the next generation, which has been introduced in 7 nm node of integrated circuit manufacturing and below. The electron mean free path of cobalt (~10 nm) is much shorter than copper’s (39 nm), thus …

Development Status Of Copper Electroplating Filling Technology In Through Glass Via For 3d Interconnections, Zhi-Jing Ji, Hui-Qin Ling, Pei-Lin Wu, Rui-Yi Yu, Da-Quan Yu, Ming Li

Journal of Electrochemistry

With the slow development of Moore's Law, the high density and miniaturization of microelectronic devices put forward higher requirements for advanced packaging technology. As a key technology in 2.5D/3D packaging, interposer technology has been extensively studied. According to different interposer materials, it is mainly divided into organic interposer, silicon interposer and glass interposer. Compared with the through silicon via (TSV) interconnection, the through glass via (TGV) interposer has received extensive attention in the 2.5D/3D advanced packaging field for its advantages of excellent high-frequency electrical characteristics, simple process, low cost, and adjustable coefficient of thermal expansion (CTE). However, the thermal conductivity …

Noncontact Liquid Crystalline Broadband Optoacoustic Sensors, Hengky Chandrahalim, Michael T. Dela Cruz

AFIT Patents

An optoacoustic sensor includes a liquid crystal (LC) cell formed between top and bottom plates of transparent material. A transverse grating formed across the LC cell that forms an optical transmission bandgap. A CL is aligned to form a spring-like, tunable Bragg grating that is naturally responsive to external agitations providing a spectral transition regime, or edge, in the optical transmission bandgap of the transverse grating that respond to broadband acoustic waves. The optoacoustic sensor includes a narrowband light source that is oriented to transmit light through the top plate, the LC cell, and the bottom plate. The optoacoustic sensor …

Photon Attenuation Layer Silicon-Based X-Ray Detector: Quantum Efficiency Investigation And Algorithmic Processing Of Individual Detection Events, Kevin Larkin

ENGS 88 Honors Thesis (AB Students)

State-of-the-art X-ray detectors either use silicon direct detection—which is inefficient, as silicon is mostly transparent to high-energy X-rays—or rely on expensive scintillators to first down-convert X-ray photons to lower energies. Dr. Eldred Lee of Dartmouth College recently completed doctoral research that suggested the promise of a novel alternative: silicon-based X-ray detectors that utilize photon attenuation layers rather than scintillators. While Dr. Lee’s work is certainly rigorous and meritorious, background noise controls were rendered less effective by circumstances. The work presented in this thesis succeeded in implementing much better background noise controls for a series of new tests to compare the …

Processing And Characterization Of Silicon Nitride For Rapid And Low-Level Detection Of Water Pathogens, Arielle H. Buchanan, Logan A. Chai

Materials Engineering

Water sanitation is a serious issue affecting the lives of many, and methods for assessing water cleanliness have been a major research interest for decades. Rapid and accurate water pathogen detection methods that can be performed in field applications have been a growing research focus, especially in low-income countries most affected by poor water quality. Silicon nitride was explored as a material for colorimetric water-pathogen sensing due to the large body of knowledge around its processing, and its isoelectric point. A bioassay of chlorophenol red-β-Dgalactopyranoside (CPRG) and β-galactosidase (β-gal) enzymes with Escherichia coli (E. coli) bacteria was used to examine …

Identification And Characterization Of Point Defects In Nonlinear Optical Crystals: Barium Gallium Selenide And Lithium Triborate, Brian C. Holloway

Theses and Dissertations

Increased interest in developing new nonlinear optical materials has led to 3rd generation materials, such as BaGa4Se₇ and LiB₃O₅. These two nonlinear optical crystals have the potential to enable development of tunable lasers operating across the mid-wave infrared and the ultraviolet regions, respectively. Coherent light sources are used in the development of enhanced technologies with commercial and defense-based applications such as: health and environmental monitoring devices, next-generation infrared countermeasures, and ballistic missile booster exhaust plume characterization. The performance of optical materials in high-powered military applications is largely limited by the presence of defects. These defects …

Model-Based Design Of An Optimal Lqg Regulator For A Piezoelectric Actuated Smart Structure Using A High-Precision Laser Interferometry Measurement System, Grant P. Gallagher

Master's Theses

Smart structure control systems commonly use piezoceramic sensors or accelerometers as vibration measurement devices. These measurement devices often produce noisy and/or low-precision signals, which makes it difficult to measure small-amplitude vibrations. Laser interferometry devices pose as an alternative high-precision position measurement method, capable of nanometer-scale resolution. The aim of this research is to utilize a model-based design approach to develop and implement a real-time Linear Quadratic Gaussian (LQG) regulator for a piezoelectric actuated smart structure using a high-precision laser interferometry measurement system to suppress the excitation of vibratory modes.

The analytical model of the smart structure is derived using the …

Spinel Transition Metal Oxide Nanoparticle-Pigmented Solar Selective Coatings With High Thermal Efficiency And High-Temperature Thermal Stability In Air, Can Xu

Dartmouth College Ph.D Dissertations

This thesis explores spinel-structure transition metal oxide nanoparticle pigmented solar selective coatings with high thermal efficiency (>90%) and high-temperature (~750 ºC) thermodynamic stability via cost-effective and facile fabrication methods. Compared to the preliminary work, we reduce the emittance loss by selecting silicones with a lower emittance loss as the matrix. We further move from purchasing simple commercial oxide nanoparticles to systematically designing and synthesizing spinel-structure based three-transition-metal-incorporated oxide nanoparticles for a better optical response of nanoparticle pigmented coatings. Nanoparticles of three systems are studied, including Ni-Mn-Fe oxide, Cu-Mn-Fe oxide, and Cu-Mn-Cr oxide systems. Among, Cu-Mn-Cr oxide nanoparticle pigmented silicone …

A Circular Economy Approach To Improve E-Waste Recycling In California: Economic Potential And Policy Options, Kripa Shah

Master's Projects and Capstones

The higher consumption rates of electronic devices along with their short life cycles and few repair options poses a huge challenge for E-waste industries to manage them effectively. E-waste comprises of hazardous materials and toxic constituents that can affect the environment and public health through improper disposal. However, they also contain few valuable materials that, if recovered, can reduce the dependence on virgin raw materials. Circular economy has the potential to utilize these valuable materials and gain environment and socio-economic benefits. The research explains how the adoption of a circular economy approach can help improve the E-waste recycling in California …

Monolithically Integrated Microscale Pressure Sensor On An Optical Fiber Tip, Jeremiah C. Williams, Hengky Chandrahalim

AFIT Patents

A passive microscopic Fabry-Pérot Interferometer (FPI) pressure sensor includes an optical fiber and a three-dimensional microscopic optical enclosure. The three-dimensional microscopic optical enclosure includes tubular side walls having lateral pleated corrugations and attached to a cleaved tip of the optical fiber to receive a light signal. An optically reflecting end wall is distally engaged to the tubular side walls to enclose a trapped quantity of gas that longitudinally positions the optically reflecting end wall in relation to ambient air pressure, changing a distance traveled by a light signal reflected back through the optical fiber.

Hinged Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Jeremiah C. Williams, Hengky Chandrahalim

AFIT Patents

A passive microscopic Fabry-Pérot Interferometer (FPI) sensor includes a three-dimensional microscopic optical structure formed on a cleaved tip of the optical fighter using a two-photon polymerization process on a photosensitive polymer by a three-dimensional micromachining device. The three-dimensional microscopic optical structure having a hinged optical layer pivotally connected to a distal portion of a suspended structure. A reflective layer is deposited on a mirror surface of the hinged optical layer while in an open position. The hinged optical layer is subsequently positioned in the closed position to align the mirror surface to at least partially reflect a light signal back …

Near-Earth Ion Irradiation Effects On Functional Ceramic Materials: A Combined Experimental-Monte Carlo Approach, William J. Sands

All Theses

The near-Earth space radiation environment is a complex system that creates a harmful environment for materials to operate in. Motivated by the search for using optical defects as an indicator of radiation damage, five single-crystal functional ceramic materials were selected to undergo ion irradiation at conditions found in the near-Earth space environment. Due to the complex nature of ion irradiation effects in ceramic materials, a host of calculations and experimental characterization methods were used. Calculations using the 2013 SRIM code were used to evaluate the ion projected range and the type and number of defects (vacancies) created by ion irradiation. …

Reactive Thin Film Polymers And Thin Film Composite Membranes For The Rapid Screening Of Uranium Isotopes, Abenazer W. Darge

All Dissertations

Traditional radiochemistry approaches for the detection of trace-level alpha-emitting radioisotopes in water require lengthy offsite sample preparations and do not lend themselves to rapid quantification. Therefore, a novel platform is needed that combines onsite purification, concentration, and isotopic screening with a fieldable detection system. My dissertation research objective was to develop novel reactive thin polymer films and thin film composite membranes for the selective separation of uranium from environmental water followed by direct isotopic analysis by alpha spectroscopy. Chapter 1 reviews progress made on uranium separation from aqueous matrices and discusses methods used for the determination of isotopic composition.

Chapter …

Porous Silicon Photonics For Label-Free Interferometric Biosensing And Flat Optics, Tahmid Hassan Talukdar

All Dissertations

This dissertation uses porous silicon as a material platform to explore novel optical effects in three domains: (i) It studies dispersion engineering in integrated waveguides to achieve high performance group index sensing. With proper design parameters, the sensor waveguides can theoretically achieve 6 times larger group index shift compared to the actual bulk effective refractive index shift. We demonstrate the guided mode confinement factor to be a key parameter in design and implementation of these waveguides. (ii) It explores multicolor laser illumination to experimentally demonstrate perceptually enhanced colorimetric sensing, overcoming the limitations faced by many contemporary colorimetric sensors. Our technique …

Design, Fabrication, And Characterization Of An Array Of Graphene Based Variable Capacitors, Millicent Nkirote Gikunda

Graduate Theses and Dissertations

Since it was first isolated and characterized in 2004, graphene has shown the potential for a technological revolution. This is due to its amazing physical properties such as high electrical conductivity, high thermal conductivity, and extreme flexibility. Freestanding graphene membranes naturally possesses an intrinsic rippled structure, and these ripples are in constant random motion even room temperatures. Occasionally, the ripples undergo spontaneous buckling (change of curvature from concave to convex and vice versa) and the potential energy associated with this is a double well potential. This movement of graphene is a potential source of vibrational energy.

In this dissertation, we …

Preparation Of Pt@Basrtio3 Nanostructure And Its Properties Towards Photoelectrochemical Ammonia Synthesis, Jing Zhang, Rui-Xia Guo, Jian-Jun Fu, Shi-Bin Yin, Pei-Kang Shen, Xin-Yi Zhang

Journal of Electrochemistry

Ammonia is an important industrial raw material and a potential green energy. Using renewable energy to convert nitrogen into ammonia under ambient condition is an attractive method. However, the development of efficient photoelectrochemical ammonia synthesis catalysts remains a challenge. Perovskite such as BaSrTiO₃ (BST) is a good photocatalytic material. However, BST is active under ultraviolet light and has a high recombination rate of photogenerated electron-hole pairs. By dispersing precious metals, it can effectively regulate the absorption of sunlight by BST. In this work, we used a two-step method to prepare BST. The H₂PtCl₆·6H₂O …

Simplified Synthesis Of Conjugated Polymers Enabled Via 1,4-Dihydropyrrolo[3,2-B]Pyrrole, Kenneth-John Jack Bell

Master of Science in Chemical Sciences Theses

Conjugated polymers have attracted significant attention as the active layer material in organic electronics, such as organic photovoltaics and light-emitting diodes, partly due to the ability to influence a broad range of properties through structural design motifs. However, high performance conjugated polymers suffer from numerous synthetic steps, generation of toxic waste, and harsh reaction conditions all of which impart additional costs that inhibit their widespread utilization. Therefore, an emphasis on reducing synthetic complexity and utilizing abundant, commercially available starting materials is needed for organic electronics to reach their full potential. Dihydropyrrolo[3,2-b]pyrrole (H₂DPP) chromophores offer a simple one-pot synthesis …

Method Of Making Hinged Self-Referencing Fabry–Pérot Cavity Sensors, Jeremiah C. Williams, Hengky Chandrahalim

AFIT Patents

A method is provided for fabricating a passive optical sensor on a tip of an optical fiber. The method includes perpendicularly cleaving a tip of an optical fiber and mounting the tip of the optical fiber in a specimen holder of a photosensitive polymer three-dimensional micromachining machine. The method includes forming a three-dimensional microscopic optical structure within the photosensitive polymer that comprises a two cavity Fabry-Perot Interferometer (FPI) having a hinged optical layer that is pivotally coupled to a suspended structure. The method includes removing an uncured portion of the photosensitive polymer using a solvent. The method includes depositing a …

Thermomechanics Of Semiconducting Polymers And Their Morphological Phenomena, Luke Galuska

Dissertations

In contrast to conventional silicon-based electronics, semiconducting polymers show great promise for emerging applications in soft, flexible, and ductile electronic technologies. This is due to their polymeric nature, tailorable structure, and sub-100 nm device thickness. Despite this mechanical novelty, there remains a poor understanding of their structure-property-processing relationships, which has hindered growth within the field. This dissertation elucidates these relationships through investigation of their thermomechanics, and morphological phenomena. This was accomplished through the following projects:

1) To demonstrate the impact of backbone rigidity on semiconducting polymer thermomechanics, we varied the backbone rigidity of an NDI-based polymer by inserting flexible methylene …

Polarization-Sensitive Optical Responses From Natural Layered Hydrated Sodium Sulfosalt Gerstleyite, Ravi P. N. Tripathi, Xiaodong Yang, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Multi-element layered materials have gained substantial attention in the context of achieving the customized light-matter interactions at subwavelength scale via stoichiometric engineering, which is crucial for the realization of miniaturized polarization-sensitive optoelectronic and nanophotonic devices. Herein, naturally occurring hydrated sodium sulfosalt gerstleyite is introduced as one new multi-element van der Waals (vdW) layered material. The mechanically exfoliated thin gerstleyite flakes are demonstrated to exhibit polarization-sensitive anisotropic linear and nonlinear optical responses including angle-resolved Raman scattering, anomalous wavelength-dependent linear dichroism transition, birefringence effect, and polarization-dependent third-harmonic generation (THG). Furthermore, the third-order nonlinear susceptibility of gerstleyite crystal is estimated by the probed …

Determination Of Nonlinear Optical Properties For Gallium Arsenide Phosphide Ternary Compounds And For Tin Thiohypodiphosphate, Peter F. Norris

Theses and Dissertations

The Department of Defense and the commercial sector rely on coherent light sources to emit light that transmits through the atmosphere. Nonlinear optical effects in crystalline materials can be used to generate the laser waves, but certain nonlinear effects negatively impact the performance of laser generating materials. This thesis focuses on characterizing nonlinear optical properties for gallium arsenide phosphide ternary compounds and for tin thiohypodiphosphate. The Maker Fringe experiment is used to determine the d-coefficients of the materials, which describe the magnitude of the nonlinear response of the material. The Z-Scan experiment is used to calculate the nonlinear refractive …

Towards The Integration Of Ferroelectric Negative Capacitance With Gallium Oxide Semiconductors For High Power Applications, Guillermo A. Salcedo

Theses and Dissertations

Gallium oxide is a relatively new semiconductor material with characteristics auspicious for high frequency and high-voltage applications. Although several research groups have already demonstrated radio-frequency (RF) devices on Ga₂O₃ with remarkable features, there is still room for improvement. For instance, the operating frequency of RF field-effect transistors (FET) decreases with the parasitic capacitance, which can be counteracted by higher gate capacitance. Implementing ferroelectric dielectrics with suitable parameters in Ga₂O₃ FET promises to enhance the gate capacitance and therefore increase operating frequency. This work investigated the effect of various factors (film composition, film thickness, TiN …

Formulation And Characterization Of Fast-Curing Plastic Scintillators With High-Z Loading, Theodore W. Stephens

Theses and Dissertations

Development of novel fast-curing plastic scintillators is highly advantageous due to their potential to be manufactured via 3D printing. Several formulations were developed that exhibit enhanced photon sensitivity, producing modest but discernible photopeaks at an incident gamma energy of 122 keV. The photon sensitivity is achieved via bismuth high-Z loading; however, this practice typically results in diminished light yields. Subsequent formulations, which varied the photoinitiator concentration and curing time, demonstrated successful curing with sufficient plastic hardness, reduced purple discoloration, reduced heat buildup during curing, and resulted in less cracking during the curing process, all of which were correlated with lower …

Design And Fabrication Of Nanostructured Electrodes For Complementary Electrochemical And Photoelectrochemical Water Splitting, Kholoud El Sayed Abousalem

Theses and Dissertations

Designing highly active, durable, and nonprecious electrodes for overall water splitting is of urgent scientific importance to realize sustainable hydrogen production. Accordingly, the need to search efficient energy production systems is of crucial necessity. In this thesis, two various systems for sustainable hydrogen production have been reported using electrochemical and photoelectrochemical pathways. In the first part of the thesis, electrochemical water splitting involving both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) has been established. To this end, an innovative approach is demonstrated to synthesize flower-like 3D homogenous trimetallic Mn, Ni, Co phosphide catalysts directly on nickel foam via …

Design And Fabrication Of A Low-Cost, Portable, Battery-Operated Surface Enhanced Raman Scattering (Sers) Optical Device, Blessing Adewumi

LSU Doctoral Dissertations

Raman Spectroscopy is a time-honored, non-invasive method for analyzing and identifying the molecular composition of materials. However, unenhanced Raman Spectroscopy has extremely low sensitivity which limits its sensing capability. SERS brings rough nano-metallic surfaces in contact with the material molecules to enormously enhance the Raman signals.

The sensitivity of SERS can be exploited in probe applications where the spectrometer needs to be brought near the specimen. For example, a long optical fiber coupled to a SERS device can be used to characterize and identify easy-to-reach cancerous tissues in organisms. Unfortunately, background signals in a long fiber can easily mask any …

Improving The Performance And Durability Of Metal Contacts In Crystalline Silicon Solar Cells Using Advanced Characterization, Nafis Iqbal

Electronic Theses and Dissertations, 2020-2023

Solar energy is one of the fastest growing forms of energy generation due to its low cost, lack of emissions, minimal maintenance, and excellent durability. However, like any other technology, it is also not free from defects and degradation, which limit its performance in the real world. Most of the degradation is related to metal contacts, which also happens to be one of the most expensive items in manufacturing, comprising almost half of the cost of converting a silicon wafer into a photovoltaic (PV) cell. Therefore, studying contact degradation to make them reliable and free of defects is the key …

A Computational Exploration Of The Scandate Cathode Surface, Shankar Miller-Murthy

Theses and Dissertations--Chemical and Materials Engineering

The exact surface configuration of scandate cathodes has been a point of contention for the materials community for a long time. Without proper understanding of it and the related structures and emission mechanisms, scandate cathodes remain patchy and unreliable emitters. Thus, density functional theory techniques were applied to various potential surface arrangements and found that there are several low-energy surfaces with low work functions that incorporate a scandium interlayer between tungsten and oxygen or otherwise have a scandium-on-tungsten structure. Furthermore, it was discovered that adding a monolayer of scandium directly to a tungsten surface is surprisingly favorable, thermodynamically. While none …

Green-Route Synthesis Of Halide Perovskite Materials And Their Optoelectronic Properties, Xiaobing Tang

Theses and Dissertations--Chemical and Materials Engineering

Colloidal semiconductor quantum dots (QDs), also called as nanocrystals (NCs), are a class of functional materials with extraordinary properties, which are different from their bulk counterparts and benefit from their exclusive quantum confinement (size) effect. Semiconductor exhibits the quantum confinement effect when the characteristic size of the semiconductor is comparable to or smaller than the de Broglie wavelength of the electron wave function and/or the exciton Bohr diameter of the bulk semiconductor. In recent years, metal halide perovskite NCs, as next-generation semiconductor materials for lighting and display, have aroused a wide attention due to their excellent optoelectronic properties. However, traditional …

An Approach For Material Model Identification Of A Composite Coating Using Micro-Indentation And Multi-Scale Simulations, Pouya Shojaei, Riccardo Scazzosi, Mohamed Trabia, Brendan O’Toole, Marco Giglio, Xing Zhang, Yiliang Liao, Andrea Manes

Mechanical Engineering Faculty Research

While deposited thin film coatings can help enhance surface characteristics such as hardness and friction, their effective incorporation in product design is restricted by the limited understand-ing of their mechanical behavior. To address this, an approach combining micro-indentation and meso/micro-scale simulations was proposed. In this approach, micro-indentation testing was conducted on both the coating and the substrate. A meso-scale uniaxial compression finite element model was developed to obtain a material model of the coating. This material model was incorporated within an axisymmetric micro-scale model of the coating to simulate the indentation. The proposed approach was applied to a Ti/SiC metal …