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In the past several decades, water pollution has increased drastically due to rapid industrialization and population growth. Water contamination with pharmaceuticals are becoming an emerging problem as even a very low concentration may... more
In the past several decades, water pollution has increased drastically due to rapid industrialization and population growth. Water contamination with pharmaceuticals are becoming an emerging problem as even a very low concentration may pose risks to human health and aquatic lifeforms. Since the safe limit of some chemicals such as painkillers and hormones in drinking water are in the range of ppm, the requirements for low-level detection of pharmaceuticals in water are demanding. Therefore, the development of new water quality monitoring sensors with improved limit-of-detection and sensitivity are critical. State-ofthe-art water quality monitoring systems include sensors for pH, free chlorine and dissolved oxygen. As opposed to conventional techniques, many novel sensors are based on electrochemical redox reactions, which are described by the Nernst equation. However, one important practical problem in realizing a highly sensitive and wide dynamic range sensor is that few ppm change...
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Energy harvesting rectennas require ultrafast rectifying diodes that are efficiently matched to the optical nanoantenna. These diodes should possess low on-resistance and high responsivity. Here, we introduce a metal-insulator-metal diode... more
Energy harvesting rectennas require ultrafast rectifying diodes that are efficiently matched to the optical nanoantenna. These diodes should possess low on-resistance and high responsivity. Here, we introduce a metal-insulator-metal diode composed of a new material, Ti-TiO2-Al. This diode has a 1.0 nm ultrathin insulator layer fabricated using atomic layer deposition (ALD). It has a zero-bias resistance of 275 Ω and a maximum responsivity of 3.1 A/W. To further improve its performance, another ultrathin layer of ZnO was added. The proposed Ti-TiO2/ZnO-Al metal-insulator-insulator-metal diode has a zero-bias resistance of 312 Ω and a maximum responsivity of 5.1 A/W. The two types of diodes are fabricated on a SiO2 substrate using conventional photolithography and ALD. Between 20 °C and 55 °C, the I-V characteristics did not show much temperature dependence. The effective barrier height, dielectric constant, and electron effective mass in each insulator are extracted using a constrain...
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In this work, the topic of the detrimental contact effects in organic thin-film transistors (OTFTs) is revisited. In this case, contact effects are considered as a tool to enhance the characterization procedures of OTFTs, achieving more... more
In this work, the topic of the detrimental contact effects in organic thin-film transistors (OTFTs) is revisited. In this case, contact effects are considered as a tool to enhance the characterization procedures of OTFTs, achieving more accurate values for the fundamental parameters of the transistor threshold voltage, carrier mobility and on-off current ratio. The contact region is also seen as a fundamental part of the device which is sensitive to physical, chemical and fabrication variables. A compact model for OTFTs, which includes the effects of the contacts, and a recent proposal of an associated evolutionary parameter extraction procedure are reviewed. Both the model and the procedure are used to assess the effect of the annealing temperature on a nickel-1,4,8,11,15,18,22,25-octakis(hexyl)phthalocyanine (NiPc6)-based OTFT. A review of the importance of phthalocyanines in organic electronics is also provided. The characterization of the contact region in NiPc6 OTFTs complement...
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Over the past few decades, we have witnessed a dramatic rise in life expectancy owing to significant advances in medical science and technology, medicine as well as increased awareness about nutrition, education, and environmental and... more
Over the past few decades, we have witnessed a dramatic rise in life expectancy owing to significant advances in medical science and technology, medicine as well as increased awareness about nutrition, education, and environmental and personal hygiene. Consequently, the elderly population in many countries are expected to rise rapidly in the coming years. A rapidly rising elderly demographics is expected to adversely affect the socioeconomic systems of many nations in terms of costs associated with their healthcare and wellbeing. In addition, diseases related to the cardiovascular system, eye, respiratory system, skin and mental health are widespread globally. However, most of these diseases can be avoided and/or properly managed through continuous monitoring. In order to enable continuous health monitoring as well as to serve growing healthcare needs; affordable, non-invasive and easy-to-use healthcare solutions are critical. The ever-increasing penetration of smartphones, coupled ...
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An inkjet printing process for depositing palladium (Pd) thin films from a highly loaded ink (>14 wt%) is reported. The viscosity and surface tension of a Pd‐organic precursor solution is adjusted using toluene to form a printable and... more
An inkjet printing process for depositing palladium (Pd) thin films from a highly loaded ink (>14 wt%) is reported. The viscosity and surface tension of a Pd‐organic precursor solution is adjusted using toluene to form a printable and stable ink. A two‐step thermolysis process is developed to convert the printed ink to continuous and uniform Pd films with good adhesion to different substrates. Using only one printing pass, a low electrical resistivity of 2.6 μΩ m of the Pd film is obtained. To demonstrate the electrochemical pH sensing application, the surfaces of the printed Pd films are oxidized for ion‐to‐electron transduction and the underlying layer is left for electron conduction. Then, solid‐state reference electrodes are integrated beside the bifunctional Pd electrodes by inkjet printing. These potentiometric sensors have sensitivities of 60.6 ± 0.1 and 57 ± 0.6 mV pH−1 on glass and polyimide substrates, and short response times of 11 and 6 s, respectively. Also, accurate...
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Recent advances of micro-electrochemical ph and free chlorine sensors are reviewed and their technological challenges and perspectives are provided.
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Research Interests: Engineering, Electrical Engineering, Computer Science, Analytical Chemistry, Telecommunications, and 15 moreSemiconductors, Medicine, Systems Integration, Sensors, Transducers, Radio Frequency, Phase Locked Loop, Cmos, Microwaves, DBC, Equipment Design, Phase Noise, Equipment Failure Analysis, Electrical And Electronic Engineering, and Direct modulation
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Semiconductor materials and devices continue to occupy a pre-eminent technological position because of their importance in building integrated electronic systems for wide ranging applications from computers, cell-phones, personal digital... more
Semiconductor materials and devices continue to occupy a pre-eminent technological position because of their importance in building integrated electronic systems for wide ranging applications from computers, cell-phones, personal digital assistants, digital cameras and electronic entertainment systems, to electronic instrumentation for medical diagnostics and environmental monitoring. A key ingredient of this technological dominance has been the rapid advances in the quality
Research Interests: Materials Engineering, Materials Science, Environmental Monitoring, Doping, Semiconductor, and 15 moreReliability, Material Processing, Energy Dissipation, Computer Applications, Low Frequency Noise, Potential Energy Surface, Input Output, Dielectric Materials, Testing Equipment, Power Dissipation, Personal Digital Assistant, Defect Density, Parasitic Resistance, Integrated system, and Digital camera
Experimental characterization and theoretical study of the interband transitions of self-assembled InAs quantum dots (QDs) grown on metamorphic pseudosubstrates of InxGa1−xAs (0.0⩽x⩽0.3) are reported. The effect of the varying underlying... more
Experimental characterization and theoretical study of the interband transitions of self-assembled InAs quantum dots (QDs) grown on metamorphic pseudosubstrates of InxGa1−xAs (0.0⩽x⩽0.3) are reported. The effect of the varying underlying strain on the size distribution of InAs QDs and their photoluminescence emission wavelength is investigated by employing different substrate compositions. Atomic force microscopy images of the QDs show that the ratio of the height/lateral diameter of the QDs decreases with decreasing strain and the photoluminescence of the buried InAs QDs shows that the peak wavelength redshifts with increasing In mole fraction of the underlying pseudosubstrates. A theoretical model based on the Green’s function technique is used to calculate the density of states (DOS) of the QDs for the different samples based on the measured dot geometries. From the DOS, the electron and hole energy levels can be obtained, yielding the possible interband transitions. Good agreeme...
Research Interests: Engineering, Physics, Materials Science, III-V Semiconductors, Applied Physics, and 12 moreSelf Assembly, X ray absorption spectroscopy, Atomic Force Microscopy, Photoluminescence, Mathematical Sciences, Physical sciences, Electron Density, Quantum Dot, Gallium Arsenide, Theoretical Model, Energy Levels, and Mole Fraction
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Research Interests: Materials Science, Quantum Physics, Nanophotonics, Electronics, Packaging, and 13 moreSystem Integration, Photonics, Nanofluidics, Nanotechnology, Surface Roughness, Copper, Materials Bonding, Silicon Wafer Bonding, Bonding, Optical physics, Fluidics, Electrical And Electronic Engineering, and Rough Surface
A triply fused porphyrin dimer bearing long alkyl chains for enhanced solubility was prepared and investigated for its ability to supramolecularly functionalize single-walled carbon nanotubes. It was found that this porphyrin dimer indeed... more
A triply fused porphyrin dimer bearing long alkyl chains for enhanced solubility was prepared and investigated for its ability to supramolecularly functionalize single-walled carbon nanotubes. It was found that this porphyrin dimer indeed binds strongly to the nanotube ...
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Tunable morphology and electrical properties of inkjet-printed Pd/PdO thin films using different thermolysis atmospheres for a Pd precursor.