Radiation is part of our life. Most people may know a radioactive source is very dangerous. But there are very few situations people are exposed to uncontrolled radionuclides above background. A radioactive source can emit gamma rays which are the highest energy type in electromagnetic radiation.[2] Gamma rays are like...
Modern communication systems often have the ability to transmit signals on multiple communication mediums (e.g., RF, visible light) or interfaces (e.g., MAC layer protocols) at the same time. While each channel has different characteristics, a centralized controller with channel condition information will be able to schedule the resource allocated to...
The increasing demand for higher data-rates in spectrum-deficient indoor WiFi networks calls for the adaptation of hybrid systems, consisting of RF and optical wireless channels. The novel hybrid WiFi Free-Space Optical (WIFO) system was introduced to enhance the wireless capacity of indoor WiFi networks. In this thesis, an optical wireless...
In the next decade, technology trends--smaller dimension, lower voltage, higher operating frequency--introduce new technical considerations and challenges for radiation effects in integrated circuits. Semiconductor based circuits and traditional dynamic random-access memories will malfunction when exposed to extreme environments, such as space and nuclear reactor. The mechanisms for radiation effect are...
With explosive growth of Internet access from smart phones and tablets, increasing bandwidth for WIFI system is badly needed. Depending on two years’ research, we produced a novel communication system called WIFO system, which integrates both RF (Radio Frequency) and FSO (Free Space Optical) techniques. WIFO system can significantly increase...
This thesis studies cooperative techniques that rely on femtocell user diversity to improve the downlink communication quality of macrocell users. We analytically analyze and evaluate the achievable performance of these techniques in the downlink of Rayleigh fading channels. We provide an approximation of both the bit-error rate (BER) and the...
The passive charge compensation (PCC) technique was introduced for switched capacitor (SC) circuit to increase the slew rate and enhance the linearity performance, as PCC techniques are used on the Delta-Sigma modulator (DSM) in ADC circuitry. The PCC technique of the project was applied to the design of a SC...
Mg-MOF-74 is one type of metal-organic frameworks (MOFs) that is widely known for its excellent CO2 uptake capacity. More intriguingly, it can be used to detect low levels of toxic gas such as CO2. Currently, most research into Mg-MOF-74 focuses on using the powder type as a CO2 absorbent because...
The rapid scaling of network bandwidth and data center throughput has motivated the wide adoption of high speed transceivers. Silicon photonics (Si-Photonic) is one of the most promising techniques to realize tightly integrated optical transceivers for next-generation high speed I O standards. This dissertation focuses on the design techniques of...
The current state of research on gossip techniques for wireless broadcasting is very limited because past research efforts have mostly focused on using gossip techniques for multicast communication. On the other hand, those research efforts that have focused on using gossip techniques for wireless broadcast communications ignore energy efficiency and...
Threshold-based time of arrival (TOA) estimation is a technique for high-precision indoor localization. Existing threshold selection methods, such as xed thresh- old and normalized threshold methods, do not consider the signal-to-noise radio (SNR) value at the receiver. This is not desired for high-precision positioning. A proper threshold value depends on...
We demonstrated a sensitive biosensor based on plasmonic metal composite nanostructures. The device can be fabricated and duplicated with ease using a novel nanoprinting technology which allows precise transfer of metal nanostructures without complicated lithography processes. The design featured by its unique material composition and sub-wavelength structures maximizes the exposure...
Low-distortion architecture is widely used in wideband discrete-time switched-capacitor delta-sigma ADC design. However, it suffers from the power-hungry active adder and critical timing for quantization and dynamic element matching (DEM). To solve this problem, this dissertation presents a delta-sigma modulator architecture with shifted loop delays. In this project, shifted loop...
The primary focus of this thesis is modifying the comprehensive depletion-mode model and extending its applicability to p-channel thin-film transistor (TFT) behavior and subthreshold (subpinchoff) operation. The comprehensive depletion-mode model accurately describes depletion-mode TFT behavior and establishes a set of equations, different from those obtained from square-law theory, which can...
The research presented herein represents an effort to combine the ultra-smooth surface of an amorphous metal thin film (AMTF) with a solution-processed dielectric synthesized via prompt inorganic condensation (PIC). Analysis of dielectric film quality is carried out via electrical measurements of metal-insulator-metal (MIM) diodes. Anneals at 500 and 700 °C...
Linear wireless sensor networks (LWSN) are special class of wireless sensor networks where sensor nodes are deployed in a straight line. Monitoring industrial pipelines, railroads, tunnels, power lines, and borders are applications of LWSNs. Wireless sensors are tiny devices with limited energy resources; therefore, efficient energy routing in LWSNs is...
Data converters are ubiquitous building blocks of a signal chain. The rapid increase in
communication and connectivity devices presents new avenues for pushing the state of
the art analog to digital converters. Techniques for improving resolution, bandwidth,
linearity and bit-error rate, while reducing the power, energy and area is the...
Inter-symbol interference is one of the major factors that make the realization of high-data-rate digital communications system complex. Current designs face two main challenges: how to efficiently utilize the available bandwidth and how to reduce the hardware complexity of the transmitter and receiver. Traditional solutions use a single-band architecture. When...
Pulsed ultra-wideband (UWB) radio uses extremely short pulses to transmit
information. Such pulses provide very fine timing information, which has led to
technological advances in high-precision localization. This thesis focuses on
techniques and experiments of Time-Difference-of-Arrival (TDOA) localization of
a large number of simultaneous sources. First, common localization techniques
such...
The stupendous growth in wireless and mobile devices in the recent years has prompted researchers to look at innovative approaches that enable effective use of the available resources. In this thesis, we propose a medium access control (MAC) protocol, referred to as EM-MAC, that enables wireless devices with multi-channel access...
Physical-Layer Network Coding (PNC) is a promising technique that has great potentials for improving the achievable data rates of end-to-end flows through higher packet transmission rates, thereby increasing the overall network throughput. In this thesis, we study the performance of the PNC transmission techniques for unidirectional end-to-end flows in multi-hop...
Despite climate change requiring the cutback of fossil fuel consumption, the world continues to increase its energy demands each year. To meet the ambitious goals outlined during the Paris Agreement in 2015, which set a goal to limit global warming to 1.5°C [1], changes in energy production methods are necessary....
Nucleation in atomic layer deposition (ALD) determines how many cycles are required to initiate growth and to form a continuous film. Nucleation has been exploited for the formation of nanoparticles, catalysts, and for area-selective ALD. Although sometimes overlooked or misrepresented in ALD reports, nucleation is also critical for multicomponent ALD...
Atomic layer deposition (ALD) is an enabling technique for many new micro- and nanoscale technologies. The self-limiting surface chemical reactions by which ALD fundamentally operates give rise to uniquely high precision (atomic) control over deposited film thickness, uniformity over large areas, and conformality over complex and extreme topographies. One such...
Metal-organic frameworks (MOFs) have gained increasing attention due to their promising applications (e.g., gas storage/separations, and catalysis) as nanoporous materials stemming from generally ultrahigh porosities and surface areas. Recently, research has shifted to synthesize MOF thin films and micropatterns that enable new applications (e.g., optoelectronics, smart coatings, and sensors).
In...
The research presented herein focuses on electrical assessment of oxide thin films as insulators. The current density-electric field (J-E) characteristics of four insulators of dramatically different electrical quality are assessed in terms of their operative electronic conduction mechanisms. Conduction in the two high-quality insulators is dominated by Ohmic conduction and...
The electrical stability of amorphous indium-gallium-zinc oxide (a-IGZO) thinfilmtransistors (TFTs) is investigated for flat-panel display applications. Althoughproducts incorporating a-IGZO TFT backplanes are already commercially available,e.g., iMac with 5K retina display, technical challenges need to be addressed for nextgenerationapplications, e.g., active-matrix organic light-emitting diode displays.Device stability is one crucial issue. The...
CIGS and CdTe based commercial thin-film solar cells (TFSCs) require an absorber thickness greater than 2 µm and 4 µm, respectively, to adequately absorb the solar spectrum. To efficiently extract photoexcited electrons, these TFSCs require relatively defect-free absorbers with high-minority carrier mobility (> 100 cm2V−1s−1) and long lifetime (> 10...
Triangulateration uses geometric distance to estimate the location of user by employing techniques like received signal strength (RSS), time-of-arrival (TOA), time-difference-of-arrival (TDOA) and image processing.
Radio frequency (RF) signal positioning using TOA or TDOA techniques generally requires timing synchronization of the anchors and/or the anchors and targets. If the desired...
As the price of broadband access service becomes more affordable, the number of homes with WiFi and public WiFi hotspots in the US are projected to increase significantly in the next few years. However, limited capacity of existing WiFi networks fail to provide adequate bandwidth for densely populated areas. Therefore,...
In the past few decades, magnetic recording has been used as a dominant solution for massive data storage due to its large capacity, excellent reliability and low cost. Nowadays, exponentially increasing user-generated information is creating a huge demand as well as great challenges for high density data storage solutions. For...
The objective of the work reported herein is to explore the impact of decreasing channel thickness on radio-frequency (RF) sputtered amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) electrical performance through the evaluation of drain current versus gate voltage (I[subscript D] − V[subscript G]) transfer curves. For a fixed set of...
The release of the IEEE802.15.6 standard has led to increased interest in low-power technologies for wireless body-area-networks (WBANs). The power dissipation, supply voltage, and die area are some of the most important criteria for successful WBAN implementations. Digital-intensive RX architectures can potentially result in sub-1V operation with significant reductions in...
IC designers are continuously facing the challenges from reduced CMOS feature sizes and supply voltages. ADCs that deliver satisfactory resolutions/speeds while utilizing the state-of-the-art technologies to save power are in high demand. The analog circuits are more and more assisted by various digital calibration techniques to get boosted performances. This...
In advanced integrated circuit (IC) processes, the metal fill inserted to meet foundry imposed density requirements degrades the performance of interconnects and passive components which ultimately affects the overall circuit performance. Accounting for this degradation through electromagnetic and equivalent circuit modeling is becoming a critical aspect of IC design. However,...
The increased use of mobile wireless devices that we have recently been witnessing, such as smartphones, tablets, e-readers, and WiFi enabled devices in general, is driving an unprecedented increase in the amount of data traffic. This fast market adoption of the wireless technology along with the tremendous success of multimedia...
Polymer electrolyte membrane (PEM) fuel cells are being studied for use as high efficiency power plants in alternative fuel vehicles. To maintain high efficiency the operating temperatures of the membranes in these fuel cells must be closely monitored and controlled. However, the environment inside of the fuel cell is not...
Metal-insulator-metal (MIM) and dual-insulator MIM (MIIM) devices are used in rectennas, hot-electron transistors, single electron transistors, resistive random access memory (RRAM), and capacitors. The performance of these devices relies heavily on the energy barrier height at each metal-insulator interface. Thus, determination of the in-situ electron energy barrier at each interface...
Due to a lack of grain boundaries, an amorphous metal thin film (AMTF) possesses advantageous mechanical properties and enhanced chemical stability that is potentially useful for thermal inkjet (TIJ) printing applications. The use of an AMTF as a TIJ resistor or cavitation plate could lead to a thinner TIJ cavitation...
We demonstrated a low-cost and high-sensitivity DNA detection method using quantum dot-fullerene based molecular beacons (MBs) and magnetic nanoparticles. The MB tethered magnetic nanoparticles can be well dispersed in analytes for efficient DNA capture and concentrated by an external magnetic field for enhanced fluorescence signal detection. The detection requires only...