DC and Microwave Analysis of Gallium Arsenide Field-Effect Transistor-Based Nucleic Acid Biosensors

Sensitive high-frequency microwave devices hold great promise for biosensor design. These devices include GaAs field effect transistors (FETs), which can serve as transducers for biochemical reactions, providing a platform for label-free biosensing. In this study, a two-dimensional numerical model of a GaAs FET-based nucleic acid biosensor is proposed and simulated. The electronic band structure, space charge density, and current-voltage relationships of the biosensor device are calculated. The intrinsic small signal parameters for the device are derived from simulated DC characteristics and used to predict AC behavior at high frequencies. The biosensor model is based on GaAs field-effect device physics, semiconductor transport equations, and a DNA charge model. Immobilization of DNA molecules onto the GaAs sensor surface results in an increase in charge density at the gate region, resulting from negatively-charged DNA molecules. In modeling this charge effect on device electrical characteristics, we take into account the pre-existing surface charge, the orientation of DNA molecules on the sensor surface, and the distance of the negative molecular charges from the sensor surface. Hybridization with complementary molecules results in a further increase in charge density, which further impacts the electrical behavior of the device. This behavior is studied through simulation of the device current transport equations. In the simulations, numerical methods are used to calculate the band structure and self-consistent solutions for the coupled Schrodinger, Poisson, and current equations. The results suggest that immobilization and hybridization of DNA biomolecules at the biosensor device can lead to measurable changes in electronic band structure and current-voltage relationships. The high-frequency response of the biosensor device shows that GaAs FET devices can be fabricated as sensitive detectors of oligonucleotide binding, facilitating the development of inexpensive semiconductor-based molecular diagnostics suitable for rapid diagnosis of various disease states

21st Century Nanostructured Materials

Nanostructured materials (NMs) are attracting interest as low-dimensional materials in the high-tech era of the 21st century. Recently, nanomaterials have experienced breakthroughs in synthesis and industrial and biomedical applications. This book presents recent achievements related to NMs such as graphene, carbon nanotubes, plasmonic materials, metal nanowires, metal oxides, nanoparticles, metamaterials, nanofibers, and nanocomposites, along with their physical and chemical aspects. Additionally, the book discusses the potential uses of these nanomaterials in photodetectors, transistors, quantum technology, chemical sensors, energy storage, silk fibroin, composites, drug delivery, tissue engineering, and sustainable agriculture and environmental applications

GeSn semiconductor for micro-nanoelectronic applications

Within the last few years the steady electronic evolution lead the semiconductor world to study innovative device architectures and new materials able to replace Si platforms. In this scenario Ge1-xSnx alloy attracts the interest of the scientific community due to its ability to tune the material bandgap as a function of Sn content and its extreme compatibility with Si processing. Although the enhanced optical properties of Ge1-xSnx are evident, the augmented electrical properties such as the higher electron and holes mobility are also beneficial for metal oxide semiconductor. Therefore the alloy is expected to be a potential solution to integrate both electrical and optical devices. On one hand, several theoretical and experimental works depict the Ge1-xSnx alloy as a novel and fascinating solution to replace Si; on the other hand the material novelty forces us to enhance the knowledge of its fundamental physical and chemical properties, re-adapting the processing steps necessary to develop electronic and optical devices. In this dissertation a comprehensive study on Ge1-xSnx has been undertaken and discussed analysing a wide range of topics. The first chapter provides a detailed theoretical study on the electronic properties of the GeSn performed using first principle methods; subsequently the data obtained have been inserted into a TCAD software in order to create and calibrate a library used to simulate electrical devices. It is important to note, that at the beginning of this PhD GeSn was not an available material in the Synopsys device software, and thus it had to be defined from scratch As a next point, since the ever decreasing device size push toward the definition of Ohmic contacts, different stanogermanide films have been thoroughly analysed using various metals (Ni, Pt and Ti) annealed with two distinct methodologies (Rapid Thermal Annealing and Laser Thermal Annealing). Subsequently, considering the material limitation such as the limited thermal budget and the Sn segregation, an exhaustive study on the material doping has been firstly discussed theoretically and after experimentally characterized using both classical ion implantation and layer deposition techniques. The different building blocks of Field Effect Transistors have been investigated and tuned individually with the aim to develop FET devices with bottom up approach. Then, Field Effect Transistor devices using GeSn NWs grown by a VLS methodology with Sn composition ranging from (0.03-0.09 at.%) have been developed and extensively characterized with the state of the art present in literature. Finally the analysis of highly selective etch recipes lead to the development of sub-nm device configuration such as Gate-All-Around (GAA) structure obtained using classical top down lithography approach. The innovative structure was electrically characterized highlighting the possibility to obtain decananometer device architecture with this innovative alloy. Lastly thesis summary and final outlooks were reported with the aim to outline the thesis contribution and the future material investigations

US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report

This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference

Bibliography of Lewis Research Center technical publications announced in 1989

This compilation of abstracts describes and indexes the technical reporting that resulted from the scientific and engineering work performed and managed by the Lewis Research Center in 1989. All the publications were announced in the 1989 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Included are research reports, journal articles, conference presentations, patents and patent applications, and theses

US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report

This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017

Bibliography of Lewis Research Center technical publications announced in 1987

This compilation of abstracts describes and indexes the technical reporting that resulted from the scientific and engineering work performed and managed by the Lewis Research Center in 1987. All the publications were announced in the 1987 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Included are research reports, journal articles, conference presentations, patents and patent applications, and theses

Silica and Silicon Based Nanostructures

Silica and silicon-based nanostructures are now well-understood materials for which the technologies are mature. The most obvious applications, such as electronic devices, have been widely explored over the last two decades. The aim of this Special Issue is to bring together the state of the art in the field and to enable the emergence of new ideas and concepts for silicon and silica-based nanostructures

1995 BRAC Commission

Naval Research Lab: Special Facilities and Equipment Capability Data Call. Tabular data, memos, documents. Box 178, L-110