Download or read book Design and Modeling of Graded Bandgap Amorphous Silicon germanium Solar Cells Fabricated by Plasma Enhanced Chemical Vapor Deposition written by Greg Charles Baldwin and published by . This book was released on 1994 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design Fabrication Characterization and Analysis of an Efficient Germanium Silicon Solar Cell for a Multi junction Solar Cell System written by Yi Wang and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The design, fabrication, characterization and analysis of low band gap germanium silicon (Ge:Si) solar cells for operation with a silicon solar cell in a multi-junction concentrator system is the objective of this thesis. This is the first report of high Ge concentration Ge:Si solar cells on Si. We achieved a Ge:Si solar cell with an efficiency of 1.37%, an open circuit voltage (Voc) of 267mV and a fill factor (FF) of 63% below Si at 30 suns. This solar cell has a short circuit current density (Jsc) of 7.91mA/cm 2 below Si at one sun after correcting for the application of an anti-reflection (AR) coating. Optical properties of Ge:Si make it a good candidate to absorb long wavelength photons which are transmitted through high or medium band gap materials, like Si. Its spectral sensitivity can reach up to 1800 nm. First principles were used to design Ge:Si solar cells and predict their photovoltaic properties below Si. Simulations show that 88% Ge concentration Ge:Si solar cells can achieve 2.3% efficiency below Si at 30 suns. High quality Ge:Si layers with high Ge concentration (above 85%) were achieved on Si substrates using reduced pressure chemical vapor deposition (RPCVD) technology. Scanning electron microscopy (SEM) was used to analyze the surface property. Secondary ion mass spectrometry (SIMS) and spreading resistance profiling (SRP) were used to monitor the germanium, impurity, and dopant concentrations. First generation Ge:Si solar cells had P type 92%Ge concentration Ge:Si absorbers grown on Si. To minimize the misfit and threading dislocations, Ge:Si graded layers were grown on Si before the growth of high Ge concentration Ge:Si. N type Si caps were grown on top of the P type Ge:Si absorbers to form the PN junction and passivate the surface. The first generation Ge:Si solar cell achieved an efficiency of 0.57% below Si at 30 suns. Through analyzing the IV (current voltage) and QE (quantum efficiency) of fabricated Ge:Si solar cells, performance improvement plans for FF were designed using the predictive models. These led to a third generation Ge:Si solar cell. A maximum efficiency of 0.79% was obtained at 88%Ge concentration below Si at 30 suns. Light trapping can increase the effective path length of photons in the solar cell. In this work, two light trapping configurations were considered. These configurations have texturing, AR coatings and back reflectors. Photon counting and ray tracing were used to evaluate their performance for Ge:Si solar cells below Si. Model indicates that the optical path length of photons with the energy near the band gap of 88% Ge concentration Ge:Si can reach 19 to 21 times that of the thickness of the Ge:Si absorber for two light trapping configurations. The fourth generation Ge:Si solar cell with the Al back reflector achieved 5.72mA/cm 2 Jsc below Si at one sun which is 60% higher than that of the third generation cell. Furthermore, the fifth generation Ge:Si solar cell with a SiO 2 /Al reflector achieved a 7.91mA/cm 2 Jsc below Si at one sun which demonstrates that the SiO 2 /Al reflector has better reflection than the Al mirror in our Ge:Si solar cells. The effective path length of photons in the fifth generation cell reached 17 times that of the thickness of the Ge:Si absorber. After increasing the Jsc of 88%Ge content Ge:Si solar cells by applying the light trapping, we achieved an efficiency of 1.3% below Si at 30 suns. This efficiency is 60% of the theoretical maximum. Moreover, the efficiency calculated by the product of best achieved Voc (373mV), Jsc (7.91mA/cm 2) and FF (66%) indicates that 88%Ge content Ge:Si solar cell can reach 1.9% efficiency below Si at 30 suns which is 80% of the theoretical maximum. This work develops the design rules that demonstrate the pathway to achieve 2.3% efficient Ge:Si solar cells below Si in a multi-junction concentrator system.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1995 with total page 736 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Next Generation Multilayer Graded Bandgap Solar Cells written by A. A. Ojo and published by Springer. This book was released on 2018-08-16 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book will guide Photovoltaics researchers in a new way of thinking about harvesting light energy from all wavelengths of the solar spectrum. It closes the gap between general solar cells books and photovoltaics journal articles, by focusing on the latest developments in our understanding of solid-state device physics. The material presented is experimental and based on II-VI thin-film materials, mainly CdTe-based solar cells. The authors describe the use of new device design, based on multilayer graded bandgap configuration, using CdTe-based solar cells. The authors also explain how the photo-generated currents can be enhanced using multi-step charge carrier production. The possibility of fabricating these devices using low-cost and scalable electroplating is demonstrated. The value of electroplating for large area electronic devices such as PV solar panels, display devices and nano-technology devices are also demonstrated. By enabling new understanding of the engineering of electroplated semiconductor materials and providing an overview of the semiconductor physics and technology, this practical book is ideal to guide researchers, engineers, and manufacturers on future solar cell device designs and fabrications. Discusses in detail the processes of growths, treatments, solar cell device fabrication and solid state physics, improving readers’ understanding of fundamental solid state physics; Enables future improvements in CdTe-based device efficiency; Explains the significance of defects in deposited semiconductor materials and interfaces that affect the material properties and resulting device performance.
Download or read book Fabrication of High Quality Low Bandgap Amorphous Silicon Amorphous Silicon Germanium Alloy Solar Cells by Chemical Annealing written by Ashutosh Shyam and published by . This book was released on 2011 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theory of Graded Bandgap Thin Film Solar Cells written by Faiz Ahmad and published by Morgan & Claypool Publishers. This book was released on 2021-08-24 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin-film solar cells are cheap and easy to manufacture but require improvements as their efficiencies are low compared to that of the commercially dominant crystalline-silicon solar cells. An optoelectronic model is formulated and implemented along with the differential evolution algorithm to assess the efficacy of grading the bandgap of the CIGS, CZTSSe, and AlGaAs photon-absorbing layer for optimizing the power-conversion efficiency of thin-film CIGS, CZTSSe, and AlGaAs solar cells, respectively, in the two-terminal single-junction format. Each thin-film solar cell is modeled as a photonic device as well as an electronic device. Solar cells with two (or more) photon-absorbing layers can also be handled using the optolelectronic model, whose results will stimulate experimental techniques for bandgap grading to enable ubiquitous small-scale harnessing of solar energy.
Download or read book Commencement written by Iowa State University and published by . This book was released on 1993 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book American Doctoral Dissertations written by and published by . This book was released on 1994 with total page 800 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thin Film Silicon Solar Cells written by Arvind Victor Shah and published by CRC Press. This book was released on 2010-08-19 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photovoltaic technology has now developed to the extent that it is close to fulfilling the vision of a "solar-energy world," as devices based on this technology are becoming efficient, low-cost and durable. This book provides a comprehensive treatment of thin-film silicon, a prevalent PV material, in terms of its semiconductor nature, startin
Download or read book High Quality 10 s Amorphous Silicon Germanium Alloy Solar Cells by Hot Wire CVD written by and published by . This book was released on 2001 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented at the 2001 NCPV Program Review Meeting: High-quality high-deposition-rate (10 angstrom/s) a-SiGe:H alloy solar cells have been made by hot-wire chemical-vapor deposition. High-quality high-deposition-rate (10 Å/s) amorphous silicon germanium (a-SiGe:H) alloy solar cells have been made by hot-wire chemical-vapor deposition (HWCVD). HW a-SiGe:H alloys are evaluated in the SS/n-i-p/ITO solar cell configuration, where the n- and i-layers are deposited by HWCVD at NREL and the p-layer by conventional glow discharge in a separate reactor by United Solar. Effects of Ge concentration, hydrogen dilution, substrate temperature, and step-wise bandgap profile in the i-layer have been studied and optimized. The best cell has an average optical bandgap of 1.6 eV with a low H-dilution at 250 C and a 3-stepwise bandgap profile where the narrowest bandgap is near the p-i interface. The best initial power output has exceeded 4 mW/cm2 under AM 1.5 illumination with a [lambda]>530-nm filter. When combining with a USSC a-Si:H top solar cell, the best double-junction solar cell exhibits an initial 11.7% active-area efficiency, and a 9.6% stable efficiency after 1000 hours of one-sun light soaking.
Download or read book Fabrication of Polycrystalline Si Solar Cells Via Aluminum Induced Crystallization of Sputtered and Plasma Enhanced Chemical Vapor Deposited Amorphous Silicon written by Albert M. Estevez and published by . This book was released on 2003 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Tuning the Bandgap of an Amorphous Sputtered Germanium Photovoltaic Cell written by Bryon Staebler and published by . This book was released on 2012 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microfabricated planar solar cells with an active solar collection area of 0.04cm2 were fabricated on n-type silicon wafers to test the viability of sputtered amorphous thin film photovoltaics for potential use in amorphous multijunction cells or inexpensive laser detectors. Several variants based on the same photovoltaic cell design were produced using amorphous silicon, amorphous germanium, and amorphous germanium-tin to explore band gap depression phenomenon in amorphous thin films that had been previously described in crystalline germanium-tin and germanium-silicon-tin alloys. UV/VIS spectroscopy and Tauc Plot band gap analysis indicated that tin inclusion led to band gap depression of 0.046 eV for every percentage increase in tin content in co-sputtered germanium-tin films. In sputtered amorphous germanium-tin films, increases in average incident photon conversion efficiency of 1.93% for Sn.05Ge. 95 and 2.95% for Sn. 10Ge. 90 as compared to germanium only films were observed. Overall cell efficiency increases were also observed with the inclusion of tin by 0.68% for Sn.05Ge. 95 and 0.78% for Sn. 10Ge. 90 when compared to germanium films. Comparing sputtered germanium films to PECVD deposited amorphous silicon films, the sputtered germanium films displayed significantly lower overall conversion efficiencies and incident photon conversion efficiencies. When comparing to amorphous silicon thin films, improved absorption of longer wavelength radiation in the IR and NIR range was expected with germanium and tin thin films exhibiting band gap depression phenomenon.
Download or read book Fabrication and Analysis of Co diffused N type Silicon Solar Cells Applying Plasma deposited Diffusion Sources written by Nadine Wehmeier and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Solar Energy written by Christoph Richter and published by Springer. This book was released on 2012-11-29 with total page 744 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gathering some 30 entries from the Encyclopedia of Sustainability Science and Technology, this book presents fundamental principles and technologies for sustainably harnessing solar energy. Covers photovoltaics, solar thermal energy, solar radiation and more.
Download or read book Fabrication of Si rich Silicon Carbide Film and Solar Cells by Low Temperature Plasma Enhanced Chemical Vapor Deposition written by 王哲夫 and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synerjy written by and published by . This book was released on 1991 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Single crystal Germanium Growth on Amorphous Silicon written by Kevin A. McComber and published by . This book was released on 2011 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: The integration of photonics with electronics has emerged as a leading platform for microprocessor technology and the continuation of Moore's Law. As electronic device dimensions shrink, electronic signals encounter crippling delays and heating issues such that signal transduction across large on-chip distances becomes increasingly more difficult. However, these issues may be mitigated by the use of photonic interconnects combined with electronic devices in electronic-photonic integrated circuits (EPICs). The electronics in proposed EPIC designs perform the logic operations and short-distance signal transmission, while photonic devices serve to transmit signals over longer lengths. However, the photonic devices are large compared to electronic devices, and thus the two types of devices would ideally exist on separate levels of the microprocessor stack in order to maximize the amount of silicon substrate available for electronic device fabrication. A CMOS-compatible back-end process for the fabrication of photonic devices is necessary to realize such a three-dimensional EPIC. Back-end processing is limited in thermal budget and does not present a single-crystal substrate for epitaxial growth, however, so high-quality crystal fabrication methods currently used for photonic device fabrication are not possible in back-end processing. This thesis presents a method for the fabrication of high-quality germanium single crystals using CMOS-compatible back-end processing. Initial work on the ultra-high vacuum chemical vapor deposition of polycrystalline germanium on amorphous silicon is presented. The deposition can be successfully performed by using a pre-growth hydrofluoric acid dip and by limiting the thickness of the amorphous silicon layer to less than 120 nm. Films deposited at temperatures of 350° C, 450° C, and 550° C show (110) texture, though the texture is most prevalent in growths at 450° C. Poly-Ge grown at 4500 C is successfully doped n-type in situ, and the grain size of as-grown material is enhanced by lateral growth over a barrier. Structures are fabricated for the growth of Ge confined in one dimension. The growths show faceting across large areas, in contrast to as-deposited poly-Ge, corresponding to enhanced grain sizes. Growth confinement is shown to reduce the defect density as the poly-Ge grows. When coalesced into a continuous film, the material grown from 1 D confinement exhibits a lower carrier density and lower trap density than as-deposited poly-Ge, indicating improved material quality. We measure an increased grain size from as-deposited poly-Ge to Ge grown from ID confinement. Single-crystal germanium is grown at 450° C from confinement in two dimensions. Such growths exhibit faceting across the entire crystal as well as the presence of E3 boundaries ({111} twins), with many growths showing no other boundaries. These twins mediate the growth of the crystal, as they serve as the points for heterogeneous surface nucleation of adatom clusters. The twins can form after the crystal nucleates and are strongly preferred in order to obtain appreciable crystal growth rates. We model the growths from the confining channels in order to find the optimum channel geometry for large, uniform, single-crystal growths that consistently emerge from the channel. The growths from 2D confinement show lower trap density than those from 1 D confinement, indicating a further enhancement of the crystal quality due to the increased confinement. This method of single-crystal growth from an amorphous substrate is extensible to any materials system in which selective non-epitaxial deposition is possible.
