Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Institution
- Publication Year
- Publication
- Publication Type
Articles 1 - 17 of 17
Full-Text Articles in Physical Sciences and Mathematics
Fabrication Of Black Phosphorus Terahertz Photoconductive Antennas, Nathan Tanner Sawyers
Fabrication Of Black Phosphorus Terahertz Photoconductive Antennas, Nathan Tanner Sawyers
Physics Undergraduate Honors Theses
Terahertz (THz) photoconductive antennas (PCAs) using 40nm thin-film flakes of black phosphorus (BP) and hexagonal boron nitride (hBN) have been shown computationally to be capable of THz emission comparable to those based on GaAs [2]. In this paper, I briefly describe the scientific and practical interest in THz emissions and explain what warrants research into black phosphorus as a photoconductive semiconductor in THz devices. Furthermore, I outline the basic principle of how these antennas work and mention alternative designs produced by other researchers in the past. Finally, I summarize the fabrication process of these antennas, as well as the measurements …
Gate-Controlled Quantum Dots In Two-Dimensional Tungsten Diselenide And One-Dimensional Tellurium Nanowires, Shiva Davari Dolatabadi
Gate-Controlled Quantum Dots In Two-Dimensional Tungsten Diselenide And One-Dimensional Tellurium Nanowires, Shiva Davari Dolatabadi
Graduate Theses and Dissertations
This work focuses on the investigation of gate-defined quantum dots in two-dimensional transition metal dichalcogenide tungsten diselenide (WSe2) as a means to unravel mesoscopic physical phenomena such as valley-contrasting physics in WSe2 flakes and its potential application as qubit, as well as realizing gate-controlled quantum dots based on elementaltellurium nanostructures which may unlock the topological nature of the host material carriers such as Weyl states in tellurium nanowires.The fabrication and characterization of gate-defined hole quantum dots in monolayer and bilayer WSe2 are reported. The gate electrodes in the device design are located above and below the WSe2 nanoflakes to accumulate …
Tailoring Interfaces And Composition For Stable And Efficient Perovskite Solar Cells, Hamza Javaid
Tailoring Interfaces And Composition For Stable And Efficient Perovskite Solar Cells, Hamza Javaid
Doctoral Dissertations
Metal halide perovskite solar cells (PSCs) have revolutionized the field of thin film photovoltaics. Within a decade, the power conversion efficiencies (PCEs) have increased at a phenomenal rate, rising from 3.8% to more than 25% in single-junction devices, moving them ahead of the current silicon-based technology. The high efficiencies of perovskite solar cells (PSCs) and their other unique properties arise from a combination of organic and inorganic components and electronic-ionic conduction, making them excellent candidates for a plethora of applications. However, PSCs face a significant—and ironic—roadblock to commercialization: these light-harvesting materials degrade under sunlight—the very condition they would need …
Design And Characterization Of Standard Cell Library Using Finfets, Phanindra Datta Sadhu
Design And Characterization Of Standard Cell Library Using Finfets, Phanindra Datta Sadhu
Master's Theses
The processors and digital circuits designed today contain billions of transistors on a small piece of silicon. As devices are becoming smaller, slimmer, faster, and more efficient, the transistors also have to keep up with the demands and needs of the daily user. Unfortunately, the CMOS technology has reached its limit and cannot be used to scale down due to the transistor's breakdown caused by short channel effects. An alternative solution to this is the FinFET transistor technology, where the gate of the transistor is a three dimensional fin that surrounds the transistor and prevents the breakdown caused by scaling …
Exploring Gated Nanoelectronic Devices Fabricated From 1d And 2d Materials, Prathamesh A. Dhakras
Exploring Gated Nanoelectronic Devices Fabricated From 1d And 2d Materials, Prathamesh A. Dhakras
Legacy Theses & Dissertations (2009 - 2024)
One and two dimensional materials are being extensively researched toward potential application as ultra-thin body channel materials. The difficulty of implementing physical doping methods in these materials has necessitated various alternative doping schemes, the most promising of which is the electrostatic gating technique due to its reconfigurability. This dissertation explores the different fundamental devices that can be fabricated and characterized by taking advantage of the electrostatic gating of individual single-walled carbon nanotubes (SWNTs), dense SWNT networks and exfoliated 2D tungsten diselenide (WSe2) flakes.
Generalizable Modeling Of Charge Transport In Single Electron Transistor Devices: Application To Thermal Sensitivity In Semiconducting Island Systems, Paniz Khanmohammadi Hazaveh
Generalizable Modeling Of Charge Transport In Single Electron Transistor Devices: Application To Thermal Sensitivity In Semiconducting Island Systems, Paniz Khanmohammadi Hazaveh
Dissertations, Master's Theses and Master's Reports
Electronic devices, especially MOSFETs, have been dimensionally scaled down to enhance operation of integrated circuits, addressing challenges such as current leakage, fluctuation of intrinsic semiconductor properties, and power dissipation. Reaching dimensions below 20 nm, there are fundamental limitations that are difficult to overcome, driving alternative device paradigms to be sought utilizing the quantum mechanical behavior of electrons. Single electron transistor (SET) devices are examples of a new generation of low-power transistors designed to transport information via single electron tunneling through one or more islands separated by tunnel junctions. Experimentally explored SET devices have shown that there are advantages to using …
Quantum Dot Band Gap Investigations, John Ryan Peterson
Quantum Dot Band Gap Investigations, John Ryan Peterson
Student Works
Improving solar panel efficiency has become increasingly important as the world searches for cheap renewable energy. Recent developments in the industry have focused on multi-layer cells, some of which use semiconducting dyes to absorb light in place of crystalline solids. In this paper, I characterize various dyes recently synthesized for use in solar panels. These dyes contain semiconducting nanoparticles enclosed primarily by the protein ferritin to limit particle size. The band gaps were measured using either optical absorption spectroscopy or measuring the photoluminescence spectrum, depending on the type of semiconductor. The results indicate that both manganese oxide and lead sulfide …
Molecular Dynamics Study On Defect Reduction Strategies Towards The Fabrication Of High Performance Cd1-Xznxte/Cds Solar Cells, Jose Juan Chavez
Molecular Dynamics Study On Defect Reduction Strategies Towards The Fabrication Of High Performance Cd1-Xznxte/Cds Solar Cells, Jose Juan Chavez
Open Access Theses & Dissertations
Cadmium Telluride is a material widely used in terrestrial thin film photovoltaic applications due to its nearly ideal band gap (~1.5 eV) and high absorption coefficient. Due to its low manufacturing cost, this technology has the potential to become a significant energy resource if higher energy conversion efficiencies are achieved. However, the module efficiencies (~14%) are still far from the theoretical maximum (~30%) for this material in a single junction configuration. The reason behind this low performance is attributed to the high number of defects that are present within the device materials. The physics behind the formation mechanisms of these …
Two-Photon Absorption In Bulk Semiconductors And Quantum Well Structures And Its Applications, Himansu Pattanaik
Two-Photon Absorption In Bulk Semiconductors And Quantum Well Structures And Its Applications, Himansu Pattanaik
Electronic Theses and Dissertations
The purpose of this dissertation is to provide a study and possible applications of two-photon absorption (2PA), in direct-gap semiconductors and quantum-well (QW) semiconductor structures. One application uses extremely nondegenerate (END) 2PA, for mid-infrared (mid-IR) detection in uncooled semiconductors. The use of END, where the two photons have very different energies gives strong enhancement comapared to degenerate 2PA. This END-2PA enhanced detection is also applied to mid-IR imaging and light detection and ranging (LIDAR) in uncooled direct-gap photodiodes. A theoretical study of degenerate 2PA (D-2PA) in quantum wells, QWs, is presented, along with a new theory of ND 2PA in …
Experimental And Theoretical Approaches To Characterization Of Electronic Nonlinearities In Direct-Gap Semiconductors, Claudiu Cirloganu
Experimental And Theoretical Approaches To Characterization Of Electronic Nonlinearities In Direct-Gap Semiconductors, Claudiu Cirloganu
Electronic Theses and Dissertations
The general goal of this dissertation is to provide a comprehensive description of the limitations of established theories on bound electronic nonlinearities in direct-gap semiconductors by performing various experiments on wide and narrow bandgap semiconductors along with developing theoretical models. Nondegenerate two-photon absorption (2PA) is studied in several semiconductors showing orders of magnitude enhancement over the degenerate counterpart. In addition, three-photon absorption (3PA) is studied in ZnSe and other semiconductors and a new theory using a Kane 4-band model is developed which fits new data well. Finally, the narrow gap semiconductor InSb is studied with regard to multiphoton absorption, free-carrier …
Nonlinear Absorption And Free Carrier Recombination In Direct Gap Semiconductors, Peter D. Olszak
Nonlinear Absorption And Free Carrier Recombination In Direct Gap Semiconductors, Peter D. Olszak
Electronic Theses and Dissertations
Nonlinear absorption of Indium Antimonide (InSb) has been studied for many years, yet due to the complexity of absorption mechanisms and experimental difficulties in the infrared, this is still a subject of research. Although measurements have been made in the past, a consistent model that worked for both picosecond and nanosecond pulse widths had not been demonstrated. In this project, temperature dependent two-photon (2PA) and free carrier absorption (FCA) spectra of InSb are measured using femtosecond, picosecond, and nanosecond IR sources. The 2PA spectrum is measured at room temperature with femtosecond pulses, and the temperature dependence of 2PA and FCA …
Integrated Inp Photonic Switches, Daniel May-Arrioja
Integrated Inp Photonic Switches, Daniel May-Arrioja
Electronic Theses and Dissertations
Photonic switches are becoming key components in advanced optical networks because of the large variety of applications that they can perform. One of the key advantages of photonic switches is that they redirect or convert light without having to make any optical to electronic conversions and vice versa, thus allowing networking functions to be lowered into the optical layer. InP-based switches are particularly attractive because of their small size, low electrical power consumption, and compatibility with integration of laser sources, photo-detectors, and electronic components. In this dissertation the development of integrated InP photonic switches using an area-selective zinc diffusion process …
Quantum Mechanical Calculations Of Monoxides Of Silicon Carbide Molecules, John W. Roberts Jr.
Quantum Mechanical Calculations Of Monoxides Of Silicon Carbide Molecules, John W. Roberts Jr.
Theses and Dissertations
Modern semiconductor devices are principally made using the element silicon. In recent years, silicon carbide (SiC), with its wide band-gap, high thermal conductivity, and radiation resistance, has shown prospects as a semiconductor material for use in high temperature and radiation environments such as jet engines and satellites. A limiting factor in the performance of many SiC semiconductor components is the presence of lattice defects formed at oxide dielectric junctions during processing. Recent theoretical work has used small quantum mechanical systems embedded in larger molecular mechanics structures to attempt to better understand SiC surfaces and bulk materials and their oxidation. This …
Electric Field Mapping System With Nanosecond Temporal Rosolution, F. E. Peterkin, R. Block, K. H. Schoenbach
Electric Field Mapping System With Nanosecond Temporal Rosolution, F. E. Peterkin, R. Block, K. H. Schoenbach
Bioelectrics Publications
The electric field dependence of the absorption coefficient in semi‐insulating GaAs at the absorption edge was measured in a high‐voltage pulsed experiment. Pulse duration was kept below 50 ns in order to avoid thermal effects. A GaAs laser diode was used as a probe light source with wavelength varied from 902 to 911 nm. For fields up to 40 kV/cm the absorption coefficient increased from 3 to 17 cm−1 at 902 nm, with smaller absolute increases evident at the longer wavelengths. Calculation from theory was consistent with this behavior. The spatial variation of the electric field was also recorded …
Supralinear Photoconductivity Of Copper Doped Semi-Insulating Gallium Arsenide, K. H. Schoenbach, R. P. Joshi, F. Peterkin, R. L. Druce
Supralinear Photoconductivity Of Copper Doped Semi-Insulating Gallium Arsenide, K. H. Schoenbach, R. P. Joshi, F. Peterkin, R. L. Druce
Bioelectrics Publications
We report on the intensity dependent supralinear photoconductivity in GaAs:Si:Cu material. The results of our measurements show that the effective carrier lifetime can change over two orders of magnitude with variations in the intensity of the optical excitation. A threshold intensity level has been observed and can be related to the occupancy of the deep copper level. Numerical simulations have also been carried out to analyze the trapping dynamics. The intensity dependent lifetimes obtained from the simulations match the experimental data very well. Finally, based on the nonlinear intensity dependence of the effective lifetimes, a possible low‐energy phototransistor application for …
Impact Of Field-Dependent Electronic Trapping Across Coulomb Repulsive Potentials On Low Frequency Charge Oscillations, R. P. Joshi, K. H. Schoenbach, P. K. Raha
Impact Of Field-Dependent Electronic Trapping Across Coulomb Repulsive Potentials On Low Frequency Charge Oscillations, R. P. Joshi, K. H. Schoenbach, P. K. Raha
Bioelectrics Publications
We have performed Monte Carlo simulations to obtain the field dependence of electronic trapping across repulsive potentials in GaAs. Such repulsive centers are associated with deep level impurities having multiply charged states. Our results reveal a field‐dependent maxima in the electronic capture coefficient, and the overall shape is seen to depend on the background electron density due to the effects of screening. Based on the Monte Carlo calculations, we have examined the stability of compensated semiconductors containing such repulsive centers. Our analysis indicates a potential for low frequency charge oscillations which is in keeping with available experimental data.
Temporal Development Of Electric Field Structures In Photoconductive Gaas Switches, K. H. Schoenbach, J. S. Kenney, F.E. Peterkin, R. J. Allen
Temporal Development Of Electric Field Structures In Photoconductive Gaas Switches, K. H. Schoenbach, J. S. Kenney, F.E. Peterkin, R. J. Allen
Bioelectrics Publications
The temporal development of the electric field distribution in semi‐insulating GaAs photoconductive switches operated in the linear and lock‐on mode has been studied. The field structure was obtained by recording a change in the absorption pattern of the switch due to the Franz–Keldysh effect at a wavelength near the band edge of GaAs. In the linear mode, a high field layer develops at the cathode contact after laser activation. With increasing applied voltage, domainlike structures become visible in the anode region and the switch transits into the lock‐on state, a permanent filamentary electrical discharge. Calibration measurements show the field intensity …