Characterization of Short-Wavelength-Selective a-Si:H MSM Photoconductors for Large-Area Digital-Imaging Applications
Photoconductor-type photodetectors are attractive as sensors due to their compatibility with thin-film-transistor (TFT) fabrication processes. Since they exhibit photogain, photoconductor detectors have better or comparable responsivity and quantum efficiency (QE) compared to p-i-n photodiodes. In this paper, the operation of metal-semiconductor-metal photoconductor-based photodetectors using aluminum electrodes and thin hydrogenated amorphous-silicon (a-Si) films is investigated. The experimental results of photocurrent measurements, as well as the responsivity and QE for different a-Si film thicknesses, bias voltages, and electrode gaps, are presented. Integration with TFT fabrication and its application in large-area digital imaging are discussed.
In It to WIN It
Nanotechnology and its applications are poised for explosive growth in the years ahead. The Waterloo Institute for Nanotechnology (WIN), with a new state-of-theart Quantum Nano Centre, a young and dynamic research faculty, and home to hundreds of Canada's best nanotechnology engineering students, is positioned to contribute to that growth as one of the foremost centers for nanoresearch and innovation in the world. From developments in advanced lithium-ion battery technologies, next-generation solar photovoltaic cells, and thermoelectric conversion materials to hybrid bionanocomposite materials and nanocatalysts, advances in fundamental understanding of materials design will lead to real-world applications. WIN anticipates major progress in organic electronic devices, large-area displays, and miniaturized CNTs or graphene-based X-ray sources. Single-electron and single-photon quantum devices enabled by nanotechnology will be fabricated and employed in quantum information processing. Handheld lab-on-a-chip diagnostic devices with microfluidic flow in channels controlled by electric fields will become a reality for disease and pathogen diagnosis, replacing more bulky and expensive analytical instrumentation. Drugs encapsulated in nanoparticles delivering therapies directly to a cancerous tissue will be in clinical trials for early adoption, and new, innovative nanotools for imaging and measurement will be introduced. These are only a few of the exciting results researchers expect to see from the next ten years of research at WIN.
The Physics of Medical Imaging
Introduction - and some challenging questions. In the beginning. Diagnostic radiology with x-rays: Introduction The imaging system and image formation Photon interactions Important physical parameters X-ray tubes Image receptors Digital radiology. Quality assurance and image improvement in diagnostic radiology with x-rays. Introduction to quality assurance: Basic quality-assurance tests for x-ray sets Specific quality-assurance tests Data collection and presentation of the results Summary of quality assurance Improvement in radiographic quality Scatter removal Contrast enhancement Summary of methods of image enhancement. X-ray transmission computed tomography: The need for sectional images The principles of sectional imaging Fourier-based solutions: The method of convolution and backprojection Iterative methods of reconstruction Other considerations. Clinical applications of X-ray computed tomography in radiotherapy planning: X-ray computed tomography scanners and their role in planning Non-standard computed tomography scanners. The physics of radioisotope imaging: Introduction Radiation detectors Radioisotope imaging equipment Radionuclides for imaging The role of computers in radioisotope imaging Static and dynamic planar scintigraphy Emission computed tomography Quality control and performance assessment of radioisotope imaging equipment Clinical applications of radioisotope imaging. Diagnostic Ultrasound: Introduction Basic physics Engineering principles of ultrasonic imaging Clinical applications and biological aspects of diagnostic ultrasound Research topics. Spatially localised nuclear magnetic resonance: Introduction The development of nuclear magnetic resonance Principles of nuclear magnetic resonance Nuclear magnetic resonance pulse sequences Relaxation processes and their measurement Nuclear magnetic resonance image acquisition and reconstruction Spatially localised spectroscopy Instrumentation Nuclear magnetic resonance safety. Physical aspects of infrared imaging: Introduction Infrared photography Transilluminaton Infrared imaging Liquid-crystal thermography Microwave thermography. Imaging of tissue electrical impedance: The electrical behaviour of tissue Tissue impedance imaging Suggested clinical applications of applied potential tomography. Imaging by diaphanography: Clinical applications Physical basis of transillumination Experimental arrangements. The mathematics of image formation and image processing: The concept of object and image The relationship between object and image The general image processing problem Discrete Fourier representation and the models for imaging systems The general theory of image restoration Image sampling Two examples of image processing from modern clinical practice Iterative image processing. Perception and interpretation of images. Introduction The eye and brain as a stage in an imaging system Spatial and contrast resolution Perception of moving images Quantitative measures of investigative performance. Computer requirements of imaging systems: Single- versus multi-user systems Generation and transfer of images Processing speed Display of medical images Three-dimensional image display: methodology Three-dimensional image display: clinical applications. Epilogue: Introduction The impact of radiation hazard on medical imaging practice Attributes and relative roles of imaging modalities References. Index.