Semiconductor and Optical Materials Commons^™

Spin Effects Of Excited States In Organic Semiconductors And Hybrid Perovskites For Optoelectronics And Spintronics, Miaosheng Wang

Doctoral Dissertations

Organic semiconductors and organic-inorganic hybrid perovskites have demonstrated versatile functionalities for optoelectronic and spintronic applications. Research in this dissertation focuses on the spin effects of excited states in emerging organic semiconductor and hybrid perovskite systems to understand the fundamental working principle. The investigation on the spin effects in excited states can provide insightful guidance for the development of the next-generation organic and hybrid perovskite optoelectronics and spintronics.

In organic semiconductors, the excited states, namely, excitons can be characterized by the total spin angular momentum S=S_e+S_h of the constituent electron and hole, which determines the …

Performance And Economics Of Solar Inverters And Module Level Power Electronics In A 1 Mw Photovoltaic System, Maxwell Criswell

Biological and Agricultural Engineering Undergraduate Honors Theses

Photovoltaic solar panels convert sunlight to electricity in the form of direct current; therefore, a necessary component of every photovoltaic system is an inverter to convert the electricity to usable alternating current. There are various commercially available inverter technologies manufactured today such as microinverters, string inverters, and central inverters, as well as module level power electronic devices such as DC optimizers that are capable of improving system performance in string and central inverter systems. This thesis compares the performance and economics of five different inverter and module level power electronic systems through model simulation using Helioscope software. The five alternatives …

Characterization Of Gesn Semiconductors For Optoelectronic Devices, Hryhorii Stanchu

Graduate Theses and Dissertations

Germanium-tin alloys with Sn compositions higher than 8 at. % to 10 at. % have recently attracted significant interest as a group IV semiconductor that is ideal for active photonics on a Si substrate. The interest is due to the fact that while at a few percent of Sn, GeSn is an indirect bandgap semiconductor, at about 8 to 10 at. % Sn, GeSn transitions to a direct bandgap semiconductor. This is at first surprising since the solid solubility of Sn in Ge under equilibrium growth conditions is limited to only about 1 at. %. However, under non-equilibrium growth conditions, …

Si-Based Germanium Tin Photodetectors For Infrared Imaging And High-Speed Detection, Huong Tran

Graduate Theses and Dissertations

Infrared (IR) radiation spans the wavelengths of the windows: (1) near-IR region ranging from 0.8 to 1.0 μm, (2) shortwave IR (SWIR) ranging from 1.0 to 3.0 μm, (3) mid-wave IR (MWIR) region covering from 3.0 to 5.0 μm, (4) longwave IR (LWIR) spanning from 8.0 to 12.0 μm, and (5) very longwave IR extending beyond 12.0 μm. The MWIR and LWIR regions are important for night vision in the military, and since the atmosphere does not absorb at these wavelengths, they are also used for free-space communications and astronomy. Automotive and defect detection in the food industry and electronic …

Development Of A Laser-Assisted Chemical Vapor Deposition (Cvd) Technique To Grow Carbon-Based Materials, Abiodun Ademola Odusanya

MSU Graduate Theses

Carbon-based materials (CBMs) including graphene, carbon nanotubes (CNT), highly ordered pyrolytic graphite (HOPG), and pyrolytic carbon (PyC) have gained so much attention in research in recent years because of their unique electronic, optical, thermal, and mechanical properties. CBMs are relatively very stable and have minimal environmental footprint. Various techniques such as mechanical exfoliation, pulsed laser deposition, and chemical vapor deposition (CVD) have been used to grow CBMs and among them thermal CVD is the most common. This study aims to explore ways of reducing the energy requirement to produce CBMs, and for that, a novel pulsed laser-assisted CVD technique had …

Simulation Of Optical Properties Of Dielectric Layers From Visible To Near Infrared Spectral Range, Andrew Cochran, Cory Conkel

ONU Student Research Colloquium

Optical properties of dielectrics play a critical role in various applications including the design and manufacture of optical components & devices such as detectors, filters, imagers, lenses, optical coatings, photonic crystals, sensors and waveguides, and solar cells. Radiative properties of varying thicknesses of different dielectrics such as Aluminum Oxide (Al2O3), Silicon Dioxide (SiO2), Indium Tin Oxide (ITO), Magnesium Fluoride (MgF2) and Silicon Nitride (Si3N4) have been simulated and compared in the range of visible to near infrared by mathematical modelling using MATLAB simulations. The results of the evolution of the radiative properties, as a function of dielectric material thickness, on …

Universal Image Segmentation For Optical Identification Of 2d Materials, Joshua Island, Randy M. Sterbentz, Kristine L. Haley

Physics & Astronomy Faculty Research

Machine learning methods are changing the way data is analyzed. One of the most powerful and widespread applications of these techniques is in image segmentation wherein disparate objects of a digital image are partitioned and classified. Here we present an image segmentation program incorporating a series of unsupervised clustering algorithms for the automatic thickness identification of two-dimensional materials from digital optical microscopy images. The program identifies mono- and few-layer flakes of a variety of materials on both opaque and transparent substrates with a pixel accuracy of roughly 95%. Contrasting with previous attempts, application generality is achieved through preservation and analysis …

Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Hengky Chandrahalim, Jonathan W. Smith

AFIT Patents

A passive microscopic Fabry-Pérot Interferometer (FPI) sensor an optical fiber a three-dimensional microscopic optical structure formed on a cleaved tip of an optical fighter that reflects a light signal back through the optical fiber. The reflected light is altered by refractive index changes in the three-dimensional structure that is subject to at least one of: (i) thermal radiation; and (ii) volatile organic compounds.

Nanoengineered Materials For Energy Conversion & Storage Applications: A Density Functional Theory Study, Ahmed Biby

Theses and Dissertations

The conventional approach for the development of novel materials has become long relative to the desired product development cycle. Thus, the sluggish pace of the development of materials within the conventional approach hinders the rapid transformation of the scientific outcomes into useful technological products. To this end, the field of hierarchical materials informatics evolved to bridge this gap. In this field, the multiscale material internal structure is considered the starting point and the core of this approach. This being said, the density functional theory (DFT) was used to generate useful materials data for the advancement of the hierarchical materials data-bases …

Uv-Ozone Oxide Treatments For High-Efficiency Silicon Photovoltaic Devices, Munan Gao

Electronic Theses and Dissertations, 2020-

Fabrication of solar cells with higher efficiency, simpler processes and lower cost is largely perceived as the ultimate goal for photovoltaic research. To reach such a goal each step needs to be refined and optimized. In this dissertation, a UV-ozone treatment is proposed as a simple and versatile process that can be applied to multiple fabrication steps for improvement. The UV-ozone cleaning method provides comparable surface cleaning quality to more expensive and hazardous industrial standard RCA clean with less chemical used. A good passivation quality was achieved on both n-type and p-type silicon wafer by a silicon oxide/aluminum oxide passivation …

Multi-Level Analysis Of Atomic Layer Deposition Barrier Coatings On Additively Manufactured Plastics For High Vacuum Applications, Nupur Bihari

Dissertations, Master's Theses and Master's Reports

While hardware innovations in micro/nano electronics and photonics are heavily patented, the rise of the open-source movement has significantly shifted focus to the importance of obtaining low-cost, functional and easily modifiable research equipment. This thesis provides a foundation of open source development of equipment to aid in the micro/nano electronics and photonics fields.

First, the massive acceptance of the open source Arduino microcontroller has aided in the development of control systems with a wide variety of uses. Here it is used for the development of an open-source dual axis gimbal system. This system is used to characterize optoelectronic properties of …

Perovskite Thin Films Annealed In Supercritical Fluids For Efficient Solar Cells, Gilbert Annohene

Theses and Dissertations

In the field of photovoltaics, scientists and researchers are working fervently to produce a combination of efficient, stable, low cost and scalable devices. Methylammonium lead trihalide perovskite has attracted intense interest due to its high photovoltaic performance, low cost, and ease of manufacture. Their high absorption coefficient, tunable bandgap, low-temperature processing, and abundant elemental constituent provide innumerable advantages over other thin film absorber materials. Since the perovskite film is the most important in the device, morphology, crystallization, compositional and interface engineering have been explored to boost its performance and stability. High temperatures necessary for crystallization of organic-inorganic hybrid perovskite films …

Nature-Inspired Material Strategies Towards Functional Devices, Sayantan Pradhan

Theses and Dissertations

Naturally sourced, renewable biomaterials possess outstanding advantages for a multitude of biomedical applications owing to their biodegradability, biocompatibility, and excellent mechanical properties. Of interest in this dissertation are silk (protein) and chitin (polysaccharide) biopolymers for the fabrication of functional biodevices. One of the major challenges restricting these materials beyond their traditional usage as passive substrate materials is the ability to combine them with high-resolution fabrication techniques. Initial research work is directed towards the fabrication of micropatterned, flexible 2D substrates of silk fibroin and chitin using bench-top photolithographic techniques. Research is focused on imparting electrochemical properties to silk proteins using conducting …

Studying The Effects Of Initial Crack Angle On The Crack Propagation In Graphene Nano-Ribbon Through Molecular Dynamics Simulations, Vijay Kumar Pathak

Dissertations, Master's Theses and Master's Reports

In this research, we have worked on the brittle fracture of graphene nano-ribbon to explore the behavior of crack propagation at different crack angles. We have performed classical Molecular Dynamics simulations using LAMMPS at ten different crack angles between 0 degrees and 45 degrees, in an increment of 5 degrees to observe the parameters that dominate the crack path. The graphene nanoribbon is loaded in the zigzag direction by pulling it in the armchair direction with a pre-existing crack in the center. We have used OVITO for the visualization of the simulation. AIREBO potential is employed in this work because …

Development Of Light Actuated Chemical Delivery Platform On A 2-D Array Of Micropore Structure, Hojjat Rostami Azmand, Hojjat Rostami Azmand

Dissertations and Theses

Localized chemical delivery plays an essential role in the fundamental information transfers within biological systems. Thus, the ability to mimic the natural chemical signal modulation would provide significant contributions to understand the functional signaling pathway of biological cells and develop new prosthetic devices for neurological disorders. In this paper, we demonstrate a light-controlled hydrogel platform that can be used for localized chemical delivery in a high spatial resolution. By utilizing the photothermal behavior of graphene-hydrogel composites confined within micron-sized fluidic channels, patterned light illumination creates the parallel and independent actuation of chemical release in a group of fluidic ports. The …

Investigation Of The Tribological Behavior Of Mineral Lubricant Using Copper Oxide Nano Additives, Ahmed A. Abdel-Rehim, Sayed Akl, Sherif Elsoudy

Mechanical Engineering

In this study, tribological properties of custom formulated and stabilized nano lubricant are investigated. Spherical CuO nanoparticles are suspended in 20W-50 mineral base lubricant using Oleic Acid (OA) as a surfactant. Three different nano lubricant concentrations with 0.2, 0.5, and 1 wt.% were analyzed through ASTM G-99 pin-on-disc tribometer standardized test under boundary/mixed lubrication regimes. The generated friction and wear analyses confirm a consolidation of tribological properties with a reduction in friction coefficient in the range of 14.59–42.92%, compared with the base lubricant. Analysis of worn surfaces (SEM/EDX) as well as (AFM) was conducted. Combined hypotheses were proposed from the …

Treated Hfo2 Based Rram Devices With Ru, Tan, Tin As Top Electrode For In-Memory Computing Hardware, Yuvraj Dineshkumar Patel

Theses

The scalability and power efficiency of the conventional CMOS technology is steadily coming to a halt due to increasing problems and challenges in fabrication technology. Many non-volatile memory devices have emerged recently to meet the scaling challenges. Memory devices such as RRAMs or ReRAM (Resistive Random-Access Memory) have proved to be a promising candidate for analog in memory computing applications related to inference and learning in artificial intelligence. A RRAM cell has a MIM (Metal insulator metal) structure that exhibits reversible resistive switching on application of positive or negative voltage. But detailed studies on the power consumption, repeatability and retention …

Preparations And Photoelectrochemical Performances Of Rgo-Tio2 Nanotubes Arrays, Ze-Yang Zhang, Lan Sun, Chang-Jian Lin

Journal of Electrochemistry

Decorating TiO₂ nanotube arrays with RGO to improve the photocatalytic activity of TiO₂ nanotube arrays has been reported. For the reported RGO-TiO₂ nanotube arrays, TiO₂ nanotube arrays were prepared by anodizing the high-purity Ti foil in an organic electrolyte for multiple-step treatments, while RGO were deposited on TiO₂ nanotube arrays by using cyclic voltammetry or other electrical reduction methods. To enhance the reduction degree and the coverage of RGO on the resultant RGO-TiO₂ nanotube arrays, in this work, the one-step electrochemical anodization in hydrofluoric acid was used to fabricate TiO₂ nanotube arrays with …

Specific Features Of Optical Fiber Cable Operation During Tension And Change Of Ambient Temperature, Dilmurod Davronbekov, Zafar Khakimov

Bulletin of TUIT: Management and Communication Technologies

This article examines the effect of longitudinal and thermoelastic deformation of an optical module on the technological reserve of an optical fiber. Analytical expressions are given for determining the lower limit of the technological margin of an optical fiber for various types of fiber-optic cable section along the axis.

Chemico-Physical Interactions In Metal Halide Perovskites, Yongtao Liu

Doctoral Dissertations

Metal halide perovskite (MHP) has attracted tremendous attention due to its success in optoelectronics, largely due to outstanding photovoltaic performance. A wide variety of characterization approaches have been used to explore the fundamentals behind the outstanding optoelectronic properties of MHP, which has yet to be unambiguously established despite considerable efforts to do so. Given the high ionic mobility in MHP, when physical phenomena are coupled with chemical changes, all behaviors will become very complex due to the strong ion migration. Therefore, chemico-physical interactions in MHP can no longer be ignored, which will be the focus of the researches in this …