Engineering Commons^™

Optical Properties Of Black Silicon - An Analysis, Suramya Sekhri

Theses

Silicon is the preeminent solar cell material of the day because it is the first semiconductor that was learned to commercialize and continues to be the principal semiconducting material used in photovoltaic technology for the manufacture of solar cells. Silicon, an indirect band gap semiconducting material, has a reflectance of about 30% in the visible range of wavelengths. Standard Silicon solar cells are not entirely useful in the infrared spectrum region. In order to enhance the performance of Silicon solar cells, reflectance losses must be minimized and absorption must be maximized. In the solar cell industry, anti-reflection (AR) coating is …

Simulation Of Electronic And Optical Properties Of Graphene, Biao Leng

Theses

Graphene is a recently discovered two-dimensional crystal. Due to its excellent electronic properties, transport properties, optical properties, and many other features, it has tremendous potential for applications in many areas. This thesis discusses the structure and properties of graphene using several different models of graphene and carries out detailed theoretical studies and calculations of its electronic and optical properties. Using two modules of Materials Studio, CASTAP and Doml3, four graphene models have been constructed. Their electronic and optical properties have also been calculated via these two modules. By comparing the results of calculations with experimental results and the literature, the …

Design, Construction And Characterization Of A Wind Tunnel, Chang Ge

Theses

The wind tunnel is the most fundamental test equipment for aircraft testing and studying aerodynamics. Because of the complexity of the test-subject's geometry, it is difficult to study the aerodynamic pattern simply based on theoretical calculations. Most of the aerodynamics experiments still use wind tunnels. The progress of the wind tunnel is highly related to the advancements in air crafts. Aircraft manufacturing has pushed the wind tunnel technology forward. Wind tunnels can be categorized by the wind speed limit differences, which are controlled by the mechanism of the driving methods, structure applications, etc. In this case, we built a small …

Analysis Of Transport Properties In A Zaz Graphene Nanoribbon Junction Using Various Dopants, Natasha Parikh

Theses

A 12 atom wide ZAZ Graphene Junction was simulated and its transport properties were analyzed. I-V curves, calculated by nonequilibrium Greens function method combined with the density functional theory under external bias, showed varying semiconducting characteristics. Further, the width of the junction also showed significant effects in the determination of the semiconducting nature. A theoretical study was performed on the semiconducting characteristics by analyzing the I-V curve and transport coefficients in the junction.

Effect Of Temperature On Tunneling And Quantum Efficiency In Cigs Solar Cells, Sizhan Liu

Theses

Utilizing the two-band approximation and Wentzel-Kramers-B ri l l oui n (WKB) approximation, by including the temperature-dependent effective masses and nonparabolicity effects, an investigation of the temperature dependent band-to-band tunneling process is discussed. In comparison with the parabolic approximation and non- parabolic approximation, the tunneling probability is strongly dependent on the non-parabolicity factor. The temperature dependence of the energy band gap, electron effective mass and light hole effective mass is investigated. The tunneling current density function is derived by a series representation of the incomplete gamma function with non-parabolic effect and its variation at low temperature is also investigated. When …

Study Of Poly (L-Lactic Acid)/Poly (D-Lactic Acid) Stereocomplex As Nucleating Agent For Poly (L- Lactic Acid) Crystallization, Yuan Lao

Theses

Poly (lactic acid) (PLA) is a biodegradable polymer with good renewability and processability. However, it has some drawbacks. The Poly (lactic acid) (PLA) stereocomplex formed via the interaction between optical isomers Poly (L-lactic acid) (PLLA) and Poly (D-lactic acid) (PDLA), provides improvements on PLA thermomechanical properties. To investigate the nucleating effect brought by the PLA stereocomplex, samples of PLLA blended with different content of PDLA are prepared by the solution casting method. With different cooling rates (5, 15, 25 °C/min), DSC non-isothermal crystallization experiments are performed. The results suggest that in the presence of the stereocomplex, the PLLA crystallization temperatures …

Measurement Of Gas Flow Through Porous Structures Using Thz Spectroscopy, Yihui Wang

Theses

Comparing THz transmission through a sample with the transmission through free-space allows one to calculate the THz absorbance of a sample. Previous studies have focused on using THz absorbance to measure the diffusion of liquid through materials. In this study, the ability of THz spectroscopy to measure the flow of gas in a porous material, packaging foam, is investigated. Specifically, Terahertz spectroscopy from 0.5 to 0.7 THz is used to measure the THz absorption of 1, 1 -difluoroethane. Several experiments are performed to test the ability of THz spectroscopy to measure the flow of gas in a porous material: (1) …

Current Measurements In Electrospinning, Clinton K. Lien

Theses

Electrospinning provides an economical method of producing nanofibers. The current carried by the main spinning jet is found to be one of the factors in determining the diameter of the fiber product. However, current sources such as the corona discharge and secondary jets will lead to a systematic overestimation of the actual current value.

In this research, experiments with different configurations are set up to investigate the influence of various parameters on the measured current. It is noticed that the measured current is nearly independent on the flow rate of the solution and the external cover. A large amount of …

Role Of Materials & Design On Performance Of Baseball Bats, Kim Benson-Worth

Theses

Baseball bat safety has become an increasing area of interest with more than 19 million people in the United States alone participating in this sport. An increase in injuries resulting from bat injuries has brought the performance of the bats into question. A review of several studies focusing on the effects of the material properties of various baseball bats designs were examined. From this review it is evident that player and spectator safety greatly rely on proper baseball bat design. There was a 30% reduction in the Multi-Piece Failures (MPF) of wooden bats once the requirement of a Slope of …

Magnetic Targeted Drug Delivery System In Gene Therapy, Weilong Lu

Theses

Drug delivery system is a method to transport the drug of the required amount accurately to the targeted diseased part. Recently, the concept of Magnetic Targeted Drug Delivery System (MTDDS), based upon magnetic particles under the action of an external magnetic field, exhibits considerable potential for a wide range of medical applications. Gene therapy is the insertion of genes into an individual's cells and tissues to treat diseases. As the recombinant virus vector has many limits and problems, more studies turn to the nonvirus vectors, which have transfection efficiency and low cytotoxicity. PLLA(poly(L lactic acid)) can be biodegradable and has …

Magnetic Iron Oxide Nanoparticles: Synthesis, Characteristics, Magnetic Behavior, And Biomedical Applications, Chengyin Fu

Theses

Magnetic iron oxide nanoparticles are attracting increasing attention due to their interesting properties that can be applied in a great number of applications such as catalysis and biomedicine. This thesis focuses on the synthesis, characteristics, and biomedical applications of iron oxide nanoparticles. The two most common iron oxides, including magnetite and maghemite, are discussed in this thesis.

For most of their applications, the magnetic behavior of iron oxide nanoparticles in a fluid is very important, especially, the high gradient magnetic separation of the particles from a nonmagnetic liquid medium, such as blood in the human body. A 2D model, which …

Simulation Of Polymer Solar Cell Characteristics By Amps-1d, Lu Zhang

Theses

Simulation of polymer solar cell characteristics is presented in this study. The solar cells are made of materials such as the following: Poly (3-hexylthiophene): [6, 6]-phenyl C61- butyric acid methylester (P3HT: PCBM) and poly[2,1,3-benzothiadiazole-4,7-diyl[4,4- bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b']dithiophene-2,6-diyl]]: [6, 6]-phenyl C₆₁- butyric acid methylester (PCPDTBT: PCBM) are used as active layer materials. Analysis of Microelectronic and Photonic Structures One Dimension (AMPS-1D) is a computer simulation tool for solar cell device characteristics. The first part of this study focuses on the performance and comparison of current-voltage (I-V) simulations of indium oxide (In₂O₃) and tin oxide (SnO₂) …

Hydrogen Storage In Pt/Carbon Nanotube Sheets, An-Yu Ma

Theses

Three types of self-assembled carbon nanotube (CNT) sheets, for example, carboxylic functionalized multi-walled CNTs (MWNTs-COOH), pure multi-walled CNTs (MWNTs), and pure single-walled CNTs (SWNTs), were prepared as substrates by ambient environment vacuum filtration of suspensions of the nanotubes. To enhance hydrogen storage on the CNTs, platinum particles were deposited on the three types of CNT sheets using two processes: electrodeposition (ED) using a DC power source and electrochemical deposition under cyclic voltammetry (CV). To verify platinum deposition on the surface of the CNT sheets, a Scanning Electron Microscope (SEM) was used to obtain images, and Energy Dispersive X-ray (EDX) spectroscopy …

Interfacially Polymerized Thin Film Composite Membranes On Microporous Polypropylene Supports For Reverse Osmosis Desalination, Chao Li

Theses

The important technique of interfacial polymerization (IP) is used to fabricate thin film composite (TFC) membranes. In experiments here, microporous polypropylene (PP) flat film membranes were used as a support for fabricating TFC membranes for reverse osmosis by the IP technique. Substantial chemical, pH, and solvent resistance is provided by porous polypropylene membranes. Therefore, it is reasonable to choose porous polypropylene membranes as supports to fabricate TFC membranes for reverse osmosis.

The external and the pore surfaces of polypropylene flat film membrane were hydrophilized first by pre-wetting with acetone, then oxidized with chromic acid solution kept at 65°C. Next, the …

Submicron Patterning Using Laser Interference Lithography, Luigi Pollara Verdoni

Theses

In this thesis, the theory, fabrication protocol, and initial results of an alternative nanopatterning technique called Interferometric Lithography (IL) are presented. Comprised of the identical process attributes of traditional projection photolithography, IL mirrors the wafer preparation and development procedures of our existing clean room capabilities. The main departure is solely in means of pattern delineation. IL is a "mask less" technique that employs the interference fringe pattern of two coherent beams, and can therefore be generated with a commercial laser. Due to its simplicity, Interferometric Lithography provides an attractive supplement to existing methods of nano-patterning.

Utilizing a 325 nm HeCd …

Characterization Of Thermally Diffused Bordie Layers On Aisi 1018 Steel : Residual Stresses (By Synchrotron Radiation) And Microhardness, Joel A. Payne

Theses

Boronization is a thermal diffusion process in which needle like boride layers are formed at the surface of the metallic substrate. The boride coatings formed by the diffusion process have high hardness and strong ware and corrosion resistance. In order for coatings of this nature to be industrially successful, their service life should be long and characterization should be extensive. Measuring the residual stresses of the coatings caters to each of these aspects.

In this study, AISI 1018 steel samples were boronized by a powder-pack process for four hours at 850°C in an argon atmosphere. Characterization techniques included coating thickness, …

Electrochemical Corrosion Testing Of Boronized And Unboronized Steels, Kranthi K. Pallegar

Theses

Boronizing is a thermo-chemical surface coating technique with which surface properties of materials are enhanced substantially. One of these properties is corrosion resistance. Corrosion resistance testing has been performed in many ways right from the traditional weight loss methods to the latest electrochemical techniques. These electrochemical techniques are more reliable and less time consuming and hence are widely accepted for corrosion testing in the industry.

In the present work, direct current (D.C) corrosion testing studies of both boronized and unboronized steels have been discussed. Three types of steels, AISI 1018, AISI 4340 and AISI 304 stainless steel, were considered for …

Boron Induced Surface Modification Of Transition Metals, Raghasudha Vangaveti

Theses

Boronizing is a thermo-chemical surface treatment of metals in which boron atoms diffuse into the metal substrate and form hard metallic borides. As a result of boronizing, several properties such as hardness, wear resistance, corrosion resistance, and high temperature oxidation resistance improve which make the metal substrate more suitable for industrial applications. These boronized parts are used in many industrial applications like ingot moulds, crucibles, biomedical implants, die-casting moulds, magnetic head applications, drawing dies etc.

The objective of this work was to investigate the influence of boronizing on the properties of transition metals. Three transition metals, tantalum, niobium and tungsten …

Surface Treatment Of Ferrous Alloys With Boron, Naruemon Suwattananont

Theses

Boronizing is a thermo-chemical surface hardening treatment in which boron atoms diffused into the metal substrate form the metallic boride layer, providing high hardness, corrosion resistance, and 3-10 times increasing service life. This type of surface treatment is widely used in many applications.

The purpose of this work was to investigate the structures and properties of boronized ferrous alloys. Three types of steels, AISI 1018 (plain low carbon steel), AISI 4340 (high strength alloy steel), and AISI 304 (austenitic stainless steel), were used for this study. The boronized AISI 1018 and AISI 4340 demonstrated the saw-tooth structure with average 75-76 …

Simultaneous Heat And Mass Transfer To A Liquid Through Two Separated Interfaces, Ku-Il Park

Theses

The oxygenator is the main element of a heart-lung machine, which takes over the work of the lungs (adding oxygen to and removing carbon dioxide from the blood) during an operation. Oxygenators function by passing oxygen through a hollow fiber (straw-like fiber), where blood gases are exchanged via tiny pores in the fiber walls. In this study, a fiber-in-fiber technology was used to design a temperature controlled blood oxygenator membrane module. A Celgard® X-10 hollow fiber was put through the lumen of a polypropylene hollow fiber having a solid wall. Both fibers are made of polypropylene and are waterproof due …

Chemical Vapor Deposition Of Polymeric Films, Chi Yu

Theses

Poly-peri-naphthalene (PPN) is a one-dimensional (1 -D) graphite polymer with unique planar ladder-like conjugated molecular structure. PPN was predicted to be a good intrinsic conductor and have high thermal stability and high environmental stability.

In this project, chemical vapor deposition (CVD) and plasma enhanced chemical vapor deposition (PECVD) of carbon films with PPN structure using PTCDA as precursor were carried out under different conditions. There is only limited information in literature on the synthesis of PPN films by PECVD process, which may allow deposition at a higher rate with lower substrate temperature. In this work the influence of deposition parameters, …

Process-Structure-Property Relationship Of A Mesogenic Bioerodible Polyarylate, Seung Uk Yoo

Theses

Polymeric biomaterials are artificially synthesized polymers designed for in-vivo use. The material must be characterized and should satisfy the requirements suitable in human bodies.

For the proper characterization of materials, it is essential to apply specific processes, analyze thermal and mechanical properties, and understand the process effect and the morphology. Thermal analysis is one of the most sophisticated and well developed techniques for polymer characterization. Turi [ 1 ] has explained about the thermal characterization of polymeric materials. Jaffe et al [2], in the chapters of characterization of fibers and films, emphasized the effect of the process history of a …

In Situ Laser Etch-Depth Monitoring Of The Deep Reactive Ion Etching Process, Yuki Imura

Theses

A laser-based method for measuring feature thickness during the deep reactive ion etching process is investigated. Interference occurs between laser beam reflections from the mask surface, the mask/silicon interface, and the exposed silicon surface of a process wafer. Information from this interference signal allows the etch process to be characterized. Three methods are investigated: laser-on-SiO₂, laser-on-photoresist, and laser-on-both SiO₂ and silicon at a mask edge.

The measured data from these experiments are found to be in good agreement with theoretical calculations. Differences in reflected beam amplitude and interference fringe frequency represent well the differences SiO₂ and …

Characterization And Corrosion Of Bcc-Tantalum Coating Deposited On Aluminum And Steel Substrate By Dc Magnetron Sputtering, Chirag Joshi

Theses

Tantalum is one of the most versatile highly refractory corrosion-resistant metals. Tantalum coating can be used as an effective corrosion barrier if it is continuous, free from defects and it adheres well to the substrate. A DC magnetron sputtering technique was used to deposit tantalum on aluminum and steel. X-ray diffraction measurements revealed that the tantalum films produced by sputtering had two crystallographic structures: a body centered cubic α-phase and a metastable tetragonal β-phase. Tough and ductile alpha phase tantalum is preferred over the hard and brittle beta phase tantalum, as a protective coating. Alpha phase coatings were successfully deposited …

Crystallographic Structure And Mechanical Properties Of Tantalum Coatings On Steel Deposited By Dc Magnetron Sputtering, Charanjeet Singh Paur

Theses

Tantalum metal exhibits excellent erosion and corrosion resistance property. Hence, tantalum coatings are investigated for protection of steel surface exposed to mechanical stresses, high temperature, and corrosive environment. Such conditions exist inside large army gun barrels. The goal of this work was to contribute to the development of technology for tantalum coating of steel, which would replace the presently used electrochemical chromium deposition. A DC magnetron sputtering process was used to deposit tantalum coatings on steel substrates. In sputtering, tantalum is deposited in two phases: ductile, body-centered cubic (bcc) phase (a-phase) and a metastable, brittle tetragonal ß-phase. Only a-phase of …

Electrical Properties Of Ultra Thin Al2o3 And Hfo2 Films As Gate Dielectrics In Mos Technology, Vishal R. Mehta

Theses

The rapidly evolving silicon industry demands devices with high-speed and low power consumption. This has led to aggressive scaling of the dimensions in metal oxide semiconductor field effect transistors (MOSFETs). The channel length has been reduced as a result of this scaling. The industry favorite, SlO₂, has reached limitations in the thickness regime of 1-1.5 nm as a gate dielectric. High-_κ gate dielectrics such as Al₂0₃ and HfO₂ and their silicates are some of the materials that may, probably, replace SlO₂, as gate dielectric in the next four to five years. …

Formation And Characterization Of N/P Shallow Junctions In Sub-Micron Mosfets, Sridhar Madishetty

Theses

Semiconductors are the burgeoning industries in today's information age. Silicon based microelectronic devices are shrinking day-by-day in accord with the scaling dimensions reported by the International Technology Roadmap for Semiconductors (ITRS). There have been many semiconductor models and simulation programs constantly keeping pace with the continuously evolving scaling dimensions, process technology, performance and cost. Electrical characterization plays a vital role in determining the electrical properties of materials and device structures. Silicon based Metal Oxide Semiconductor Field Effect Transistor (MOSFET) forms the basis of Complimentary Metal Oxide Semiconductor (CMOS) circuits. Today's aggressive scaling approaches in silicon Integrated Circuit (IC) technology require …

Formation & Characterization Of P/N Shallow Junctions In Sub-Micron Mosfets, Samrat G. Chawda

Theses

The formation of shallow junctions in the source and drain regions is a major challenge to the continued success of scaling of complementary metal oxide semiconductors (CMOS) circuits. The formation of these device structures requires low-energy ion implantation and rapid thermal annealing (RTA). One of the processes which has been shown to be advantageous is spike annealing, with fast ramping and short dwell time at maximum temperature. This work is a study of the effects of implant energy, implant dose and annealing cycles on the reverse-bias leakage current in the diode junction. The reversebias leakage is the study of junction …

Characterization Of Alpha And Beta Phases Of Tantalum Coatings, Anto Yohannan

Theses

Sputtered tantalum forms two phases - α and β. The α and β phases have distinctly different crystalline structures and properties. The structure and the causes of formation of the β phase are still being studied by researchers. This is a study to distinguish and characterize these two phases. Samples from Bennet Labs and NJIT were characterized using techniques such as SEM, EDX, XRF, XRD, TEM and XAFS. Samples deposited at NJIT were used for an experimental study on the conditions favoring the formation of the phases, by depositing tantalum on heated steel and silicon substrates, additionally TEM analysis was …

Deposition Of Tantalum On Steel By Sputtering, Bhavin Shah

Theses

Recent interest in tantalum deposition comes from two different applications. One is in microelectronics where thin tantalum films (< 1 µm) are used as diffusion barrier layers for copper interconnects. The other involves its application as a material for corrosion and wear resistant coating on surfaces that are subjected to high stresses and harsh chemical and erosive environments.

This thesis is a part of the investigation done at the Ion Beam and Thin Film Research Laboratory at NJIT to study the deposition conditions and properties of tantalum thin films. It includes the design and construction of Planar D.C. Magnetron Sputtering System and Cylindrical D.C. Magnetron Sputtering System for deposition on the planar and cylindrical surfaces of steel, respectively. The electrical characteristics of the cylindrical system were tested in a range of pressures and conditions for initiation and maintaining of …