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Multi Wavelength Characterization Of Cadmium Telluride Solar Cell Development Of Q Ebic And Nsom Measurement Techniques
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Book Synopsis Multi-wavelength Characterization of Cadmium Telluride Solar Cell -- Development of Q-EBIC and NSOM Measurement Techniques by : Anthony Giacomo Gianfrancesco
Download or read book Multi-wavelength Characterization of Cadmium Telluride Solar Cell -- Development of Q-EBIC and NSOM Measurement Techniques written by Anthony Giacomo Gianfrancesco and published by . This book was released on 2013 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Thin-film inorganic solar cells, such as CdTe, have demonstrated the most promise to date for a viable low-cost renewable energy resource. Their current performance, however, is far from the theoretical limit suffering from significant charge recombination losses due to grain boundaries and point defects. It is likely that the microscopic compositions of grain bulk and grain boundaries are significantly different and not optimal for the overall device performance. Good understanding of charge transport along and across the grain boundaries and other microscopic interfaces is lacking, preventing the development of reliable and predictive device models. The insufficient microscopic understanding hinders efficient characterization of photovoltaic materials and also holds back the development of process control techniques. We first show preliminary results for a novel technique, quantum-dot electron-beam induced current to characterize semiconductors in the near-field. We also propose the use of near-field optical scanning microscopy for high precision optical excitation and for local, high-resolution characterization. These imaging techniques are examined with the goal of synthesizing information obtained by both methods, of material phenomena at the relevant length scales, to other measurement methods. The most important nanoscale phenomena being the separation of compositional and electrical effects.
Book Synopsis Cadmium Telluride Quantum Dots by : John Donegan
Download or read book Cadmium Telluride Quantum Dots written by John Donegan and published by CRC Press. This book was released on 2016-04-19 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last two decades, semiconductor quantum dots-small colloidal nanoparticles-have garnered a great deal of scientific interest because of their unique properties. Among nanomaterials, CdTe holds special technological importance as the only known II-VI material that can form conventional p-n junctions. This makes CdTe very important for the dev
Book Synopsis Novel Materials, Grid Design Rule, and Characterization Methods for Multi-junction Solar Cells by : Jingjing Li
Download or read book Novel Materials, Grid Design Rule, and Characterization Methods for Multi-junction Solar Cells written by Jingjing Li and published by . This book was released on 2012 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation addresses challenges pertaining to multi-junction (MJ) solar cells from material development to device design and characterization. Firstly, among the various methods to improve the energy conversion efficiency of MJ solar cells using, a novel approach proposed recently is to use II-VI (MgZnCd)(SeTe) and III-V (AlGaIn)(AsSb) semiconductors lattice-matched on GaSb or InAs substrates for current-matched subcells with minimal defect densities. CdSe/CdTe superlattices are proposed as a potential candidate for a subcell in the MJ solar cell designs using this material system, and therefore the material properties of the superlattices are studied. The high structural qualities of the superlattices are obtained from high resolution X-ray diffraction measurements and cross-sectional transmission electron microscopy images. The effective bandgap energies of the superlattices obtained from the photoluminescence (PL) measurements vary with the layer thicknesses, and are smaller than the bandgap energies of either the constituent material. Furthermore, The PL peak position measured at the steady state exhibits a blue shift that increases with the excess carrier concentration. These results confirm a strong type-II band edge alignment between CdSe and CdTe. The valence band offset between unstrained CdSe and CdTe is determined as 0.63 eV±0.06 eV by fitting the measured PL peak positions using the Kronig-Penney model. The blue shift in PL peak position is found to be primarily caused by the band bending effect based on self-consistent solutions of the Schrödinger and Poisson equations. Secondly, the design of the contact grid layout is studied to maximize the power output and energy conversion efficiency for concentrator solar cells. Because the conventional minimum power loss method used for the contact design is not accurate in determining the series resistance loss, a method of using a distributed series resistance model to maximize the power output is proposed for the contact design. It is found that the junction recombination loss in addition to the series resistance loss and shadowing loss can significantly affect the contact layout. The optimal finger spacing and maximum efficiency calculated by the two methods are close, and the differences are dependent on the series resistance and saturation currents of solar cells. Lastly, the accurate measurements of external quantum efficiency (EQE) are important for the design and development of MJ solar cells. However, the electrical and optical couplings between the subcells have caused EQE measurement artifacts. In order to interpret the measurement artifacts, DC and small signal models are built for the bias condition and the scan of chopped monochromatic light in the EQE measurements. Characterization methods are developed for the device parameters used in the models. The EQE measurement artifacts are found to be caused by the shunt and luminescence coupling effects, and can be minimized using proper voltage and light biases. Novel measurement methods using a pulse voltage bias or a pulse light bias are invented to eliminate the EQE measurement artifacts. These measurement methods are nondestructive and easy to implement. The pulse voltage bias or pulse light bias is superimposed on the conventional DC voltage and light biases, in order to control the operating points of the subcells and counterbalance the effects of shunt and luminescence coupling. The methods are demonstrated for the first time to effectively eliminate the measurement artifacts.
Book Synopsis Advanced Characterization Techniques for Thin Film Solar Cells by : Daniel Abou-Ras
Download or read book Advanced Characterization Techniques for Thin Film Solar Cells written by Daniel Abou-Ras and published by John Wiley & Sons. This book was released on 2016-07-13 with total page 760 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book focuses on advanced characterization methods for thin-film solar cells that have proven their relevance both for academic and corporate photovoltaic research and development. After an introduction to thin-film photovoltaics, highly experienced experts report on device and materials characterization methods such as electroluminescence analysis, capacitance spectroscopy, and various microscopy methods. In the final part of the book simulation techniques are presented which are used for ab-initio calculations of relevant semiconductors and for device simulations in 1D, 2D and 3D. Building on a proven concept, this new edition also covers thermography, transient optoelectronic methods, and absorption and photocurrent spectroscopy.
Book Synopsis Mercury Cadmium Telluride by : Peter Capper
Download or read book Mercury Cadmium Telluride written by Peter Capper and published by John Wiley & Sons. This book was released on 2011-06-20 with total page 610 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mercury cadmium telluride (MCT) is the third most well-regarded semiconductor after silicon and gallium arsenide and is the material of choice for use in infrared sensing and imaging. The reason for this is that MCT can be ‘tuned’ to the desired IR wavelength by varying the cadmium concentration. Mercury Cadmium Telluride: Growth, Properties and Applications provides both an introduction for newcomers, and a comprehensive review of this fascinating material. Part One discusses the history and current status of both bulk and epitaxial growth techniques, Part Two is concerned with the wide range of properties of MCT, and Part Three covers the various device types that have been developed using MCT. Each chapter opens with some historical background and theory before presenting current research. Coverage includes: Bulk growth and properties of MCT and CdZnTe for MCT epitaxial growth Liquid phase epitaxy (LPE) growth Metal-organic vapour phase epitaxy (MOVPE) Molecular beam epitaxy (MBE) Alternative substrates Mechanical, thermal and optical properties of MCT Defects, diffusion, doping and annealing Dry device processing Photoconductive and photovoltaic detectors Avalanche photodiode detectors Room-temperature IR detectors
Book Synopsis Improving Performance in Cadmium Telluride Solar Cells by : Geethika Kaushalya Liyanage
Download or read book Improving Performance in Cadmium Telluride Solar Cells written by Geethika Kaushalya Liyanage and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polycrystalline Cadmium Telluride has been developed to be one of the most commercially successful materials for photovoltaic module production with power conversion efficiencies over 21% for research cells to over 18% for module efficiencies. However, little is known about these record devices architecture or the processing methods. Following conventional understanding of a CdTe solar cell operation, researchers have put extensive efforts over the years to improve the CdTe device performance through improved material quality and diode quality. While this have gained some benefit, performance limiting factors to these devices remains unchanged. Deviating from conventional concepts, better understanding of the device physics is needed in order to further improve these devices. This dissertation focusses on identifying these loss mechanisms and setting guidelines to fabricating high efficiency CdTe devices through both experimental and numerical simulation. Experimental work discusses the details to construction and characterization of a CdTe deposition system and employing the new understanding of improving the CdTe device to achieve high performing CdTe devices. Here the traditional CdS window layer is replaced by a wide bandgap MgxZn1-xO to increase the photocurrent generation with better band alignment. With optimum deposition and processing conditions, work demonstrates a device with power conversion efficiency >16%. With a good front contact, performance of the device can be limited by the poor back contact. Expanding the understanding to front contact band alignment, characteristics of a back buffer layer suitable for CdTe back contact is also explored. Through 1D numerical simulation of the conduction and valence band offset, doping levels of the CdTe and back buffer layer material, this dissertation work sets the guideline to achieving CdTe device performance up to 25%.
Book Synopsis Non-Uniformities in Thin-Film Cadmium Telluride Solar Cells Using Electroluminescence and Photoluminescence: Preprint by :
Download or read book Non-Uniformities in Thin-Film Cadmium Telluride Solar Cells Using Electroluminescence and Photoluminescence: Preprint written by and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is the purpose of this research to develop specific imaging techniques that have the potential to be fast, in-line tools for quality control in thin-film CdTe solar cells. Electroluminescence (EL) and photoluminescence (PL) are two techniques that are currently under investigation on CdTe small area devices made at Colorado State University. It is our hope to significantly advance theunderstanding of EL and PL measurements as applied to CdTe. Qualitative analysis of defects and non-uniformities is underway on CdTe using EL, PL, and other imaging techniques.
Book Synopsis Electrical Characterization of Thin Film CdTe Solar Cells by : Darshini Desai
Download or read book Electrical Characterization of Thin Film CdTe Solar Cells written by Darshini Desai and published by . This book was released on 2007 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photovoltaic device modeling results obtained using AMPS (Analysis of microelectronic and photonic structures) suggest that the dominant recombination mechanism is the SRH recombination through midgap states.
Book Synopsis Development of Cathodoluminescence Spectrum Imaging Characterization of CdTe Solar Cells by : John Moseley
Download or read book Development of Cathodoluminescence Spectrum Imaging Characterization of CdTe Solar Cells written by John Moseley and published by . This book was released on 2016 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Characterization of Cadmium Zinc Telluride Solar Cells by : Gowri Sivaraman
Download or read book Characterization of Cadmium Zinc Telluride Solar Cells written by Gowri Sivaraman and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Different post deposition heat treatments were carried out to determine their effect on film and device properties. Characterization of the CZT devices was done using XRD, EDS, SIMS, J-V and spectral response measurements. CZT (Eg%7E1.7 eV) /CdS exhibited best performance when compared to the other window layers investigated. The best device exhibited Voc=640mV, FF=40% and Jsc=4.5 mA/cm2. The theoretical performance of CZT based solar cells were investigated using SCAPS. The effect of bulk and interface defects on the device parameters were studied.
Book Synopsis Mercury Cadmium Telluride by : Peter Capper
Download or read book Mercury Cadmium Telluride written by Peter Capper and published by Wiley. This book was released on 2010-11-03 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mercury cadmium telluride (MCT) is the third most well-regarded semiconductor after silicon and gallium arsenide and is the material of choice for use in infrared sensing and imaging. The reason for this is that MCT can be ‘tuned’ to the desired IR wavelength by varying the cadmium concentration. Mercury Cadmium Telluride: Growth, Properties and Applications provides both an introduction for newcomers, and a comprehensive review of this fascinating material. Part One discusses the history and current status of both bulk and epitaxial growth techniques, Part Two is concerned with the wide range of properties of MCT, and Part Three covers the various device types that have been developed using MCT. Each chapter opens with some historical background and theory before presenting current research. Coverage includes: Bulk growth and properties of MCT and CdZnTe for MCT epitaxial growth Liquid phase epitaxy (LPE) growth Metal-organic vapour phase epitaxy (MOVPE) Molecular beam epitaxy (MBE) Alternative substrates Mechanical, thermal and optical properties of MCT Defects, diffusion, doping and annealing Dry device processing Photoconductive and photovoltaic detectors Avalanche photodiode detectors Room-temperature IR detectors
Book Synopsis Characterization of Deep Level States in Cadmium Telluride Thin-film Solar Cells by the Steady-state Photocapacitance Method by : Toru Takamiya
Download or read book Characterization of Deep Level States in Cadmium Telluride Thin-film Solar Cells by the Steady-state Photocapacitance Method written by Toru Takamiya and published by . This book was released on 2005 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Characterization of Large Area Cadmium Telluride Films and Solar Cells Deposited on Moving Substrates by Close Spaced Sublimation by : Vishwanath Kumar
Download or read book Characterization of Large Area Cadmium Telluride Films and Solar Cells Deposited on Moving Substrates by Close Spaced Sublimation written by Vishwanath Kumar and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Films deposited under various conditions were studied to improve our understanding of the influence of processing conditions on device performance. The key advantage of this technique over others is its high deposition rate, simplicity of operation and high conversion efficiency. Typical deposition times were two minutes and could be reduced to as low as 45 sec with little variation in performance. The four major parameters that influence the films prepared by close spaced sublimation, namely substrate temperature, source temperature, ambient pressure, and spacing were optimized for best device performance. The influence of each parameter on deposition rate and cell efficiency was also studied. The best cells produced by this technology had an efficiency of 13% with Voc=830 mV, FF= 74% and Jsc=21.1 mA/cm2.
Book Synopsis Characterization of Cadmium Telluride Grain Boundaries in Cadmium Telluride/cadmium Sulfide Solar Cells by : Lawrence M. Woods
Download or read book Characterization of Cadmium Telluride Grain Boundaries in Cadmium Telluride/cadmium Sulfide Solar Cells written by Lawrence M. Woods and published by . This book was released on 2000 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Varying Cadmium Telluride Growth Temperature During Deposition to Increase Solar Cell Reliability by :
Download or read book Varying Cadmium Telluride Growth Temperature During Deposition to Increase Solar Cell Reliability written by and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A method for forming thin films or layers of cadmium telluride (CdTe) for use in photovoltaic modules or solar cells. The method includes varying the substrate temperature during the growth of the CdTe layer by preheating a substrate (e.g., a substrate with a cadmium sulfide (CdS) heterojunction or layer) suspended over a CdTe source to remove moisture to a relatively low preheat temperature. Then, the method includes directly heating only the CdTe source, which in turn indirectly heats the substrate upon which the CdTe is deposited. The method improves the resulting CdTe solar cell reliability. The resulting microstructure exhibits a distinct grain size distribution such that the initial region is composed of smaller grains than the bulk region portion of the deposited CdTe. Resulting devices exhibit a behavior suggesting a more n-like CdTe material near the CdS heterojunction than devices grown with substrate temperatures held constant during CdTe deposition.
Book Synopsis Characterization of Cadmium Zinc Telluride Solar Cells by RF Sputtering by : Senthilnathan Subramanian
Download or read book Characterization of Cadmium Zinc Telluride Solar Cells by RF Sputtering written by Senthilnathan Subramanian and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Characterization of the films was done using transmission response, X-ray diffraction (XRD), Atomic Force Microscopy (AFM), Secondary Electron Microscopy (SEM), current-voltage (I-V) and spectral response measurements. CZT deposited on CdS/SnOb2.
Book Synopsis Properties of Thin Film Cadmium Sulfide Used in Cadmium Telluride/cadmium Sulfide Solar Cell by : Xiawa Wu
Download or read book Properties of Thin Film Cadmium Sulfide Used in Cadmium Telluride/cadmium Sulfide Solar Cell written by Xiawa Wu and published by ProQuest. This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: CdTe/CdS solar cell is one of the promising low cost high efficiency thin film solar cells. In this work, thin film CdS properties and the effect of CdS surface conditions on CdTe growth and performance of polycrystalline CdTe/CdS thin film solar cells are investigated. Thin film CdS optical, structural and chemical properties both as deposited and after CdCl 2 heat treatment are measured. CdS surface chemical state is studied by analyzing its surface chemistry after different surface treatments. Qualitative and quantitative measurements indicate sulfate and sulfite phases on thin film CdS surfaces as well as single crystal CdS, caused by oxidation in the air. The degree of CdS oxidation is highly dependent on thermal treatment ambient, temperature and time. Results indicate reduction in grain size and smoother morphology for CdTe deposited on heavily oxidized CdS compared to chemically reduced CdS surface. Solar cell open circuit voltage is much lower on cells with heavily oxidized CdS surface.
