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NEGATIVE BIAS TEMPERATURE INSTABILITY AND CHARGE TRAPPING EFFECTS ON ANALOG AND DIGITAL CIRCUIT RELIABILITY
Title
NEGATIVE BIAS TEMPERATURE INSTABILITY AND CHARGE TRAPPING EFFECTS ON ANALOG AND DIGITAL CIRCUIT RELIABILITY.
Creator
Yu, Yixin, Yuan, Jiann. S., University of Central Florida
Abstract / Description
Nanoscale p-channel transistors under negative gate bias at an elevated temperature show threshold voltage degradation after a short period of stress time. In addition, nanoscale (45 nm) n-channel transistors using high-k (HfO2) dielectrics to reduce gate leakage power for advanced microprocessors exhibit fast transient charge trapping effect leading to threshold voltage instability and mobility reduction. A simulation methodology to quantify the circuit level degradation subjected to...
Show moreNanoscale p-channel transistors under negative gate bias at an elevated temperature show threshold voltage degradation after a short period of stress time. In addition, nanoscale (45 nm) n-channel transistors using high-k (HfO2) dielectrics to reduce gate leakage power for advanced microprocessors exhibit fast transient charge trapping effect leading to threshold voltage instability and mobility reduction. A simulation methodology to quantify the circuit level degradation subjected to negative bias temperature instability (NBTI) and fast transient charge trapping effect has been developed in this thesis work. Different current mirror and two-stage operation amplifier structures are studied to evaluate the impact of NBTI on CMOS analog circuit performances for nanoscale applications. Fundamental digital circuit such as an eleven-stage ring oscillator has also been evaluated to examine the fast transient charge transient effect of HfO2 high-k transistors on the propagation delay of ring oscillator performance. The preliminary results show that the negative bias temperature instability reduces the bandwidth of CMOS operating amplifiers, but increases the amplifier's voltage gain at mid-frequency range. The transient charge trapping effect increases the propagation delay of ring oscillator. The evaluation methodology developed in this thesis could be extended to study other CMOS device and circuit reliability issues subjected to electrical and temperature stresses.
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Date Issued
2007
Identifier
CFE0001930, ucf:47432
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001930
STUDY OF NANOSCALE CMOS DEVICE AND CIRCUIT RELIABILITY
Title
STUDY OF NANOSCALE CMOS DEVICE AND CIRCUIT RELIABILITY.
Creator
Yu, Chuanzhao, Yuan, Jiann S., University of Central Florida
Abstract / Description
The development of semiconductor technology has led to the significant scaling of the transistor dimensions -The transistor gate length drops down to tens of nanometers and the gate oxide thickness to 1 nm. In the future several years, the deep submicron devices will dominate the semiconductor industry for the high transistor density and the corresponding performance enhancement. For these devices, the reliability issues are the first concern for the commercialization. The major reliability...
Show moreThe development of semiconductor technology has led to the significant scaling of the transistor dimensions -The transistor gate length drops down to tens of nanometers and the gate oxide thickness to 1 nm. In the future several years, the deep submicron devices will dominate the semiconductor industry for the high transistor density and the corresponding performance enhancement. For these devices, the reliability issues are the first concern for the commercialization. The major reliability issues caused by voltage and/or temperature stress are gate oxide breakdown (BD), hot carrier effects (HCs), and negative bias temperature instability (NBTI). They become even more important for the nanoscale CMOS devices, because of the high electrical field due to the small device size and high temperature due to the high transistor densities and high-speed performances. This dissertation focuses on the study of voltage and temperature stress-induced reliability issues in nanoscale CMOS devices and circuits. The physical mechanisms for BD, HCs, and NBTI have been presented. A practical and accurate equivalent circuit model for nanoscale devices was employed to simulate the RF performance degradation in circuit level. The parameter measurement and model extraction have been addressed. Furthermore, a methodology was developed to predict the HC, TDDB, and NBTI effects on the RF circuits with the nanoscale CMOS. It provides guidance for the reliability considerations of the RF circuit design. The BD, HC, and NBTI effects on digital gates and RF building blocks with the nanoscale devices – low noise amplifier, oscillator, mixer, and power amplifier, have been investigated systematically. The contributions of this dissertation include: It provides a thorough study of the reliability issues caused by voltage and/or temperature stresses on nanoscale devices – from device level to circuit level; The more real voltage stress case – high frequency (900 MHz) dynamic stress, has been first explored and compared with the traditional DC stress; A simple and practical analytical method to predict RF performance degradation due to voltage stress in the nanoscale devices and RF circuits was given based on the normalized parameter degradations in device models. It provides a quick way for the designers to evaluate the performance degradations; Measurement and model extraction technologies, special for the nanoscale MOSFETs with ultra-thin, ultra-leaky gate oxide, were addressed and employed for the model establishments; Using the present existing computer-aided design tools (Cadence, Agilent ADS) with the developed models for performance degradation evaluation due to voltage or/and temperature stress by simulations provides a potential way that industry could use to save tens of millions of dollars annually in testing costs. The world now stands at the threshold of the age of nanotechnology, and scientists and engineers have been exploring here for years. The reliability is the first challenge for the commercialization of the nanoscale CMOS devices, which will be further downscaling into several tens or ten nanometers. The reliability is no longer the post-design evaluation, but the pre-design consideration. The successful and fruitful results of this dissertation, from device level to circuit level, provide not only an insight on how the voltage and/or temperature stress effects on the performances, but also methods and guidance for the designers to achieve more reliable circuits with nanoscale MOSFETs in the future.
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Date Issued
2006
Identifier
CFE0000948, ucf:46746
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000948
Effects of Electronic Media Messages on the Perceived Self-Efficacy of Pedestrian Commuters Living in the Unincorporated Central Florida Community of Conway
Title
Effects of Electronic Media Messages on the Perceived Self-Efficacy of Pedestrian Commuters Living in the Unincorporated Central Florida Community of Conway.
Creator
Stephens, Daniel, Yu, Chia-Yuan, Martin, Lawrence, Hawkins, Christopher, Seigler, Daniel, University of Central Florida
Abstract / Description
Urban pedestrianism is increasingly perceived as a dangerous form of travel. While roadway design has been historically scaled to cars instead of people, planning professionals are now re-thinking their approach to make roads more inclusive for all travelers. Scholars, however, have learned harbored fear can trump behavior even under ideal travel conditions. Such fear can adversely impact perceived pedestrian self-efficacy, which is the self-generated internal assessment or belief in a...
Show moreUrban pedestrianism is increasingly perceived as a dangerous form of travel. While roadway design has been historically scaled to cars instead of people, planning professionals are now re-thinking their approach to make roads more inclusive for all travelers. Scholars, however, have learned harbored fear can trump behavior even under ideal travel conditions. Such fear can adversely impact perceived pedestrian self-efficacy, which is the self-generated internal assessment or belief in a traveler's agentive abilities to navigate the travel environment. The challenge thus becomes twofold: improve the built environment while bolstering traveler confidence. The following study, therefore, employed a qualitative phenomenological research design to ascertain the concerns and perceptions of vulnerable travelers as it pertained to and was affected by travel-specific media. The study employed denizens selected from the Central Florida community of Conway, who were interviewed using a multi-method approach employing a semi-structured interview technique utilizing individual interviews and small focus group sessions. Using Social Cognitive Theory (SCT) as the theoretical framework, the researcher studied and documented the elements contributing to the perceptions of pedestrian travelers. The rationale for this approach is found in the dynamic relationships that exist between the objective travel environment, the perceived travel environment, and travel behavior (-) all representing the triad of cognition, the external environment, and social stimuli, which encompass Bandura's Triadic Reciprocal Determinism (TRD). The four themes that emerged from the data analysis (-) communication, safety, cost, and happiness (-) characterize the experiences of the participants as they watched positively-themed media images modeling civil travel behavior. This research adds to existing literature on the magnitude such themes have on perception, to include latent perceptions harbored by pedestrian commuters concerning dangers (-) real or imagined (-) of traveling on local roadways.
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Date Issued
2018
Identifier
CFE0007376, ucf:52100
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007376
Design, Synthesis, Stability, and Photocatalytic Studies of Sustainable Metal-Organic Frameworks
Title
Design, Synthesis, Stability, and Photocatalytic Studies of Sustainable Metal-Organic Frameworks.
Creator
Logan, Matthew, Uribe Romo, Fernando, Zhai, Lei, Yuan, Yu, Kuebler, Stephen, Rahman, Talat, University of Central Florida
Abstract / Description
The presented dissertation focuses on the design, synthesis, and characterization of metal-organic frameworks (MOFs) composed of earth-abundant elements the exhibit photoredox activity and studied their application as heterogeneous photocatalysts in organic synthesis and in solar-to-chemical energy conversion. In particular, the structure-property relationships of titanium-based MOFs relating the structure of the organic building unit and the photophysical and photochemical activity of the...
Show moreThe presented dissertation focuses on the design, synthesis, and characterization of metal-organic frameworks (MOFs) composed of earth-abundant elements the exhibit photoredox activity and studied their application as heterogeneous photocatalysts in organic synthesis and in solar-to-chemical energy conversion. In particular, the structure-property relationships of titanium-based MOFs relating the structure of the organic building unit and the photophysical and photochemical activity of the solid material is studied. The first novel family of seven MOFs isoreticular to MIL-125-NH2, includes functionalized with N-alkyl groups with increasing chain length (methyl to heptyl) and with varying connectivity (primary or secondary). The functionalized materials displayed reduced optical bandgaps correlated with the increased inductive donor ability of the alkyl substituents, enhanced excited-state lifetimes, mechanistic information towards visible light CO2 reduction, and improved water stability. The second family of titanium MOFs was prepared with a new secondary building unit and organic links of varying lengths, for which Their crystal structure was solved utilizing powder X-ray diffraction crystallography. This work provides guidelines for the next generation of photocatalyst for the conversion of solar-to-chemical energy and other organic transformations.
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Date Issued
2018
Identifier
CFE0007219, ucf:52217
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007219
Predictors of hospital quality and efficiency
Title
Predictors of hospital quality and efficiency.
Creator
Fotovvat, Hoda, Wan, Thomas, Liu, Albert Xinliang, Ramirez, Bernardo, Yu, Chia-Yuan, University of Central Florida
Abstract / Description
American hospitals have made serious efforts to implement and expand their health information technology capabilities and to integrate different specialized care or high-tech services in order to maximize the efficiency and quality of care. In providing a variety of HIT-related services, these hospitals expanded their national reputation in line with integrated care goals. As a result, hospitals are encouraged to establish effective communication channels to facilitate patient-physician...
Show moreAmerican hospitals have made serious efforts to implement and expand their health information technology capabilities and to integrate different specialized care or high-tech services in order to maximize the efficiency and quality of care. In providing a variety of HIT-related services, these hospitals expanded their national reputation in line with integrated care goals. As a result, hospitals are encouraged to establish effective communication channels to facilitate patient-physician sharing of the patient care experience, to enhance effective pain management, and to transform patient-centered care modalities to solidify the adequacy of patient care processes. By analyzing national data sets publicly available, this investigation explored the relationship of acute-care hospitals' performance to the contextual, organizational and patient characteristics, using a cross-sectional study design. This study developed and evaluated the quality and efficiency of hospitals with respects to the structural complexity, process adequacy, efficiency, and quality of care. The structure-process-outcome theory in quality of care developed by Donabedian (1980), is adopted for this investigation. Statistical methods such as confirmatory factor analysis (CFA) and covariance structure model are employed. The population surveyed by the American Hospital Association (AHA) are acute care hospitals throughout the United States, including more than 3000 acute care hospitals of all types of ownership. The data provided by HIMSS Analytics and AHA are available for 2015 and the data provided CMS quality indicators are available for 2016. The key finding of this research is that process adequacy mediates the relationship between hospital structure and performance variables. The efficiency variable played an important role in shaping quality. The location and hospital teaching status have a moderate impact in determining hospital performance by affecting the structure and process of hospitals.
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Date Issued
2019
Identifier
CFE0007888, ucf:52796
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007888
Investigating New Guaiazulenes and Diketopyrropyrroles for Photonic Applications
Title
Investigating New Guaiazulenes and Diketopyrropyrroles for Photonic Applications.
Creator
Ghazvini Zadeh, Ebrahim, Belfield, Kevin, Campiglia, Andres, Yuan, Yu, Zou, Shengli, Cheng, Zixi, University of Central Florida
Abstract / Description
?-Conjugated systems have been the focus of study in recent years in order to understand their charge transport and optical properties for use in organic electronic devices, fluorescence bioimaging, sensors, and 3D optical data storage (ODS), among others. As a result, several molecular building blocks have been designed, allowing new frontiers to be realized. While various successful building blocks have been fine-tuned at both the electronic and molecular structure level to provide advanced...
Show more?-Conjugated systems have been the focus of study in recent years in order to understand their charge transport and optical properties for use in organic electronic devices, fluorescence bioimaging, sensors, and 3D optical data storage (ODS), among others. As a result, several molecular building blocks have been designed, allowing new frontiers to be realized. While various successful building blocks have been fine-tuned at both the electronic and molecular structure level to provide advanced photophysical and optoelectronic characteristics, the azulene framework has been under-appreciated despite its unique electronic and optical properties. Among several attributes, azulenes are vibrant blue naturally occurring hydrocarbons that exhibit large dipolar character, coupled with stimuli-responsive behavior in acidic environments. Additionally, the non-toxic nature and the accompanying eco-friendly feature of some azulenes, namely guaiazulene, may set the stage to further explore a more (")green(") route towards photonic and conductive materials.The first part of this dissertation focuses on exploiting guaiazulene as a natural building block for the synthesis of chromophores with varying stimuli-responsiveness. Results described in Chapter 1 show that extending the conjugation of guaiazulene through its seven-membered ring methyl group with aromatic substituents dramatically impacts the optical properties of the guaiazulenium carbocation. Study of these ?(-)stabilized tropilium ions enabled establishing photophysical structure-property trends for guaiazulene-terminated ?-conjugated analogs under acidic conditions, including absorption, emission, quantum yield, and optical band gap patterns. These results were exploited in the design of a photosensitive polymeric system with potential application in the field of three dimensional (3D) optical data storage (ODS).Chapter 2 describes the use of guaiazulene reactive sites (C-3 and C-4 methyl group) to generate a series of cyclopenta[ef]heptalenes that exhibit strong stimuli-responsive behavior. The approach presents a versatile route that allows for various substrates to be incorporated into the resulting cyclopenta[ef]heptalenes, especially after optimization that led to devising a one-pot reaction toward such tricyclic systems. Examining the UV-vis absorption profiles in neutral and acidic media showed that the extension of conjugation at C(4) of the cyclopenta[ef]heptalene skeleton results in longer absorption maxima and smaller optical energy gaps. Additionally, it was concluded that these systems act as sensitizers of a UV-activated ((<) 300 nm) photoacid generator (PAG), via intermolecular photoinduced electron transfer (PeT), upon which the PAG undergoes photodecomposition resulting in the generation of acid.In a related study, the guaiazulene methyl group at C-4 was employed to study the linear and nonlinear optical properties of 4-styrylguaiazulenes, having the same ?(-)donor with varying ?-spacer. It was realized that the conjugation length correlates with the extent of bathochromic shift of the protonated species. On the other hand, a trend of decreasing quantum yield was established for this set of 4-styrylguaiazulenes, which can be explained by the increasingly higher degree of flexibility.The second part of this dissertation presents a comprehensive investigation of the linear photophysical, photochemical, and nonlinear optical properties of diketopyrrolopyrrole (DPP)-based derivatives, including two-photon absorption (2PA), femtosecond transient absorption, stimulated emission spectroscopy, and superfluorescence phenomena. The synthetic feasibility, ease of modification, outstanding robustness, and attractive spectroscopic properties of DPPs have motivated their study for fluorescence microscopy applications, concluding that the prepared DPP's are potentially suitable chromophores for high resolution stimulated emission depletion (STED) microscopy.
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Date Issued
2015
Identifier
CFE0006034, ucf:50986
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006034
RF Energy Harvesting for Implantable ICs with On-chip Antenna
Title
RF Energy Harvesting for Implantable ICs with On-chip Antenna.
Creator
Liu, Yu-chun, Yuan, Jiann-Shiun, Gong, Xun, Jones, W, University of Central Florida
Abstract / Description
Nowadays, as aging population increasing yearly, the health care technologies for elder people who commonly have high blood pressure or Glaucoma issues have attracted much attention. In order to care of those people, implantable integrated circuits (ICs) in human body are the direct solution to have 24/7 days monitoring with real-time data for diagnosis by patients themselves or doctors. However, due to the small size requirement for the implanted ICs located in human organs, it's quite...
Show moreNowadays, as aging population increasing yearly, the health care technologies for elder people who commonly have high blood pressure or Glaucoma issues have attracted much attention. In order to care of those people, implantable integrated circuits (ICs) in human body are the direct solution to have 24/7 days monitoring with real-time data for diagnosis by patients themselves or doctors. However, due to the small size requirement for the implanted ICs located in human organs, it's quite challenging to integrate with transmitting and receiving antenna in a single chip, especially operating in 5.8-GHz ISM band. This research proposes a new idea to solve the issue of integrating an on-chip antenna with implanted ICs. By adding an additional dielectric substrate upon the layer of silicon oxide in CMOS technology, utilizing the metal-6, it can form an extremely compact 3D-structure on-chip antenna which is able to be placed in human eye, heart or even in a few mm-diameter vessels. The proposed 3D on-chip antenna is only 1(&)#215;1(&)#215;2.8 mm3 with -10 dB gain and 10% efficiency, which has capability to communicate at least within 5 cm distance. The entire implanted battery-less wireless system has also been developed in this research. A designed 30% efficiency Native NMOS rectifier could generate 1 V and 1 mA to supply the designed low power transmitter including voltage-controlled oscillator (VCO) and power amplifier (PA). The entire system performance is well evaluated by link budget analysis and the simulation result demonstrates the possibility and feasibility of future on-demand easy-to-design implantable SoC.
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Date Issued
2014
Identifier
CFE0005202, ucf:50652
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005202
Enhanced Hardware Security Using Charge-Based Emerging Device Technology
Title
Enhanced Hardware Security Using Charge-Based Emerging Device Technology.
Creator
Bi, Yu, Yuan, Jiann-Shiun, Jin, Yier, DeMara, Ronald, Lin, Mingjie, Chow, Lee, University of Central Florida
Abstract / Description
The emergence of hardware Trojans has largely reshaped the traditional view that the hardware layer can be blindly trusted. Hardware Trojans, which are often in the form of maliciously inserted circuitry, may impact the original design by data leakage or circuit malfunction. Hardware counterfeiting and IP piracy are another two serious issues costing the US economy more than $200 billion annually. A large amount of research and experimentation has been carried out on the design of these...
Show moreThe emergence of hardware Trojans has largely reshaped the traditional view that the hardware layer can be blindly trusted. Hardware Trojans, which are often in the form of maliciously inserted circuitry, may impact the original design by data leakage or circuit malfunction. Hardware counterfeiting and IP piracy are another two serious issues costing the US economy more than $200 billion annually. A large amount of research and experimentation has been carried out on the design of these primitives based on the currently prevailing CMOS technology.However, the security provided by these primitives comes at the cost of large overheads mostly in terms of area and power consumption. The development of emerging technologies provides hardware security researchers with opportunities to utilize some of the otherwise unusable properties of emerging technologies in security applications. In this dissertation, we will include the security consideration in the overall performance measurements to fully compare the emerging devices with CMOS technology.The first approach is to leverage two emerging devices (Silicon NanoWire and Graphene SymFET) for hardware security applications. Experimental results indicate that emerging device based solutions can provide high level circuit protection with relatively lower performance overhead compared to conventional CMOS counterpart. The second topic is to construct an energy-efficient DPA-resilient block cipher with ultra low-power Tunnel FET. Current-mode logic is adopted as a circuit-level solution to countermeasure differential power analysis attack, which is mostly used in the cryptographic system. The third investigation targets on potential security vulnerability of foundry insider's attack. Split manufacturing is adopted for the protection on radio-frequency (RF) circuit design.
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Date Issued
2016
Identifier
CFE0006264, ucf:51041
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006264