DOCSLIB.ORG

Progress in Hot-Wire Deposited Nanocrystalline Silicon Solar Cells

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Progress in Hot-Wire Deposited Nanocrystalline Silicon Solar Cells DEPARTAMENT DE FÍSICA APLICADA I ÒPTICA Av. Diagonal, 647, 08028 Barcelona PROGRESS IN HOT-WIRE DEPOSITED NANOCRYSTALLINE SILICON SOLAR CELLS Marta Fonrodona Turon Memòria presentada per optar al grau de Doctor Barcelona, juny de 2003 DEPARTAMENT DE FÍSICA APLICADA I ÒPTICA Av. Diagonal, 647, 08028 Barcelona PROGRESS IN HOT-WIRE DEPOSITED NANOCRYSTALLINE SILICON SOLAR CELLS Marta Fonrodona Turon Programa de doctorat: Tècniques Instrumentals de la Física i la Ciència de Materials Bienni: 1998-2000 Tutor: Enric Bertran Serra Director: Joan Bertomeu i Balagueró Memòria presentada per optar al grau de Doctor Barcelona, juny de 2003 A la Pepeta, la Núria i tots els que hi ha entremig. This work has been carried out in the Laboratory of Thin Film Materials of the Department of Applied Physics and Optics of the University of Barcelona, supervised by Dr. Joan Bertomeu Balagueró, in the framework of the projects TIC98-0381-C0201 and MAT2001-3541-C03-01 of the CICYT of the Spanish Government , and also with the aid of the project JOR3-CT97-0126 in the JOULE programme of the European Commission. The stage at Utrecht University was possible thanks to grant 2001BEAI200159 of Generalitat de Catalunya. Progress in Hot-Wire deposited nanocrystalline silicon solar cells 1 &RQWHQWV Agraïments ............................................................................................................................3 1- Introduction .......................................................................................................................5 1.1- Thin film silicon technology .................................................................................5 1.2- Nanocrystalline silicon .........................................................................................6 1.3- Hot-Wire Chemical Vapour Deposition ...............................................................7 1.4- Hot-Wire CVD research at Universitat de Barcelona ..........................................8 1.5- Aim and outlook of this thesis ............................................................................10 2- The HWCVD set-up. Characterisation techniques .........................................................13 2.1- The HWCVD set-up ...........................................................................................13 2.2- Strategies against contaminants. Set-up modifications ......................................15 2.2.1- External heater .......................................................................................15 2.2.2- The funnel ..............................................................................................17 2.3- The wire ..............................................................................................................18 2.4- Characterisation techniques ................................................................................21 2.4.1- Morphology and structural properties ....................................................21 2.4.2- Compositional analysis ..........................................................................22 2.4.3- Optical and electrical properties .............................................................23 2.4.4- Device characterisation ..........................................................................24 3- The search of a more chemically stable material ............................................................27 3.1-Initial approaches .................................................................................................27 3.1.1- Hydrogen dilution ..................................................................................30 3.1.2- Substrate temperature .............................................................................31 3.2- The role of the filament . .....................................................................................32 3.2.1- Structural properties ...............................................................................32 3.2.2- Oxygen incorporation after deposition ..................................................35 3.2.3- Application to solar cell .........................................................................40 3.3- The protective funnel ..........................................................................................42 3.3.1- O incorporation during growth ...............................................................42 3.3.2- Effect of the process pressure ................................................................44 3.3.3- Effect of the hydrogen dilution ..............................................................46 3.3.4- Essay on a solar cell ...............................................................................48 4- Substrate influence and doped layers ..............................................................................51 4.1- Introduction ........................................................................................................51 4.2- Intrinsic material .................................................................................................52 4.2.1- Glass as substrate. Effect of DH .............................................................52 4.2.2- Substrate dependence .............................................................................54 4.3- Doped material ...................................................................................................58 4.3.1- Substrate dependence .............................................................................58 4.3.2- Scaling to device size .............................................................................61 5- Solar cells ........................................................................................................................65 2 Contents 5.1- Leakage currents ................................................................................................66 5.2- Light confinement ..............................................................................................68 5.2.1- Front contact ..........................................................................................69 5.2.2- Back reflector .........................................................................................73 5.3- HW nc-Si:H solar cells .......................................................................................74 5.3.1- Structural properties ...............................................................................75 5.3.2- Stability of the devices ...........................................................................77 5.3.3- Best results and perspectives .................................................................84 Conclusions .........................................................................................................................87 Annexe I: Shutterless deposition of phosphorous-doped microcrystalline silicon by HWCVD ..............................................................................................................................91 I.1- Motivation and experimental set-up ...................................................................91 I.2- Results and discussion ........................................................................................92 I.2.1- Thickness homogeneity ..........................................................................93 I.2.2- Effect of the starting sequence ................................................................93 I.2.3- Effect of the thickness ............................................................................95 I.2.4- The role of the filament temperature ......................................................96 I.3- Conclusions .........................................................................................................97 Annexe II: Low Temperature Cat-CVD .............................................................................99 II.1- Motivation .........................................................................................................99 II.2- Design of the catalytic tube ...............................................................................99 II.3- H2 decomposition ............................................................................................101 II.4- Si deposition ....................................................................................................103 Annexe III: Variable Illumination Measurement technique (VIM) ..................................107 III.1- Qualitative approach ......................................................................................107 III.2- Defect evaluation using VIM .........................................................................110 III.3- Solar cell analysis from the Vc curve .............................................................111 References .........................................................................................................................115 Acronym list ......................................................................................................................121 Figure list ..........................................................................................................................123 Table list ............................................................................................................................129 Resum en català ................................................................................................................131
Load more

Recommended publications
  • A Dissertation Entitled Spectroscopic Ellipsometry Studies of Thin Film Si
    A Dissertation entitled Spectroscopic Ellipsometry Studies of Thin Film Si:H Materials in Photovoltaic Applications from Infrared to Ultraviolet by Laxmi Karki Gautam Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Doctor of Philosophy Degree in Physics _________________________________________ Dr. Nikolas J. Podraza, Committee Chair _________________________________________ Dr. Robert W. Collins, Committee Member _________________________________________ Dr. Randall Ellingson, Committee Member _________________________________________ Dr. Song Cheng, Committee Member _________________________________________ Dr. Rashmi Jha, Committee Member _________________________________________ Dr. Patricia R. Komuniecki, Dean College of Graduate Studies The University of Toledo May, 2016 Copyright 2016, Laxmi Karki Gautam This document is copyrighted material. Under copyright law, no parts of this document may be reproduced without the expressed permission of the author. An Abstract of Spectroscopic Ellipsometry Studies of Thin Film Si:H Materials in Photovoltaic Applications from Infrared to Ultraviolet by Laxmi Karki Gautam Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Doctor of Philosophy Degree in Physics The University of Toledo May 2016 Optimization of thin film photovoltaics (PV) relies on the capability for characterizing the optoelectronic and structural properties of each layer in the device over large areas and correlating these properties with device performance. This work builds heavily upon that done previously by us, our collaborators, and other researchers. It provides the next step in data analyses, particularly that involving study of films in device configurations maintaining the utmost sensitivity within those same device structures. In this Dissertation, the component layers of thin film hydrogenated silicon (Si:H) solar cells on rigid substrate materials have been studied by real time spectroscopic ellipsometry (RTSE) and ex situ spectroscopic ellipsometry (SE).
    [Show full text]
  • Crystalline-Silicon Solar Cells for the 21St Century
    May 1999 • NREL/CP-590-26513 Crystalline-Silicon Solar Cells for the 21st Century Y.S. Tsuo, T.H. Wang, and T.F. Ciszek Presented at the Electrochemical Society Annual Meeting Seattle, Washington May 3, 1999 National Renewable Energy Laboratory 1617 Cole Boulevard Golden, Colorado 80401-3393 NREL is a U.S. Department of Energy Laboratory Operated by Midwest Research Institute ••• Battelle ••• Bechtel Contract No. DE-AC36-98-GO10337 NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Available to DOE and DOE contractors from: Office of Scientific and Technical Information (OSTI) P.O. Box 62 Oak Ridge, TN 37831 Prices available by calling 423-576-8401 Available to the public from: National Technical Information Service (NTIS) U.S. Department of Commerce 5285 Port Royal Road Springfield, VA 22161 703-605-6000 or 800-553-6847 or DOE Information Bridge http://www.doe.gov/bridge/home.html Printed on paper containing at least 50% wastepaper, including 20% postconsumer waste CRYSTALLINE-SILICON SOLAR CELLS FOR THE 21ST CENTURY Y.S.
    [Show full text]
  • Photoluminescent Si-Based Nanocrystals Prepared by Pulsed Laser Ablation in Low-Pressure Helium-Nitrogen Mixtures for Biomedical Applications A
    Photoluminescent Si-based nanocrystals prepared by pulsed laser ablation in low-pressure helium-nitrogen mixtures for biomedical applications A. Yu. Kharin, A. A. Fronya, S. V. Antonenko, N. V. Karpov, S. I. Derzhavin, Y. I. Dombrovska, A. A. Garmash, N. I. Kargin, S. M. Klimentov, V. Yu. Timoshenko, et al. To cite this version: A. Yu. Kharin, A. A. Fronya, S. V. Antonenko, N. V. Karpov, S. I. Derzhavin, et al.. Photoluminescent Si-based nanocrystals prepared by pulsed laser ablation in low-pressure helium-nitrogen mixtures for biomedical applications. SPIE LASE, Feb 2020, San Francisco, United States. 10.1117/12.2551482. hal-03100819 HAL Id: hal-03100819 https://hal.archives-ouvertes.fr/hal-03100819 Submitted on 6 Jan 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Photoluminescent Si-based nanocrystals prepared by pulsed laser ablation in low-pressure helium-nitrogen mixtures for biomedical applications A. Yu. Kharina*, A. A. Fronyaa, S. V. Antonenkob, N. V. Karpova, S. I. Derzhavina,c, Y. I. Dombrovskaa, A. A. Garmasha, N. I. Karginb, S. M. Klimentova, V. Yu. Timoshenkoa,d , and A.V. Kabashina,e a MEPHI, Institute of Engineering Physics for Biomedicine, Kashirskoe sh.
    [Show full text]
  • From Thin-Film to Perovskite/C-Si Tandem Solar Cell Applications
    coatings Article Versatility of Nanocrystalline Silicon Films: from Thin-Film to Perovskite/c-Si Tandem Solar Cell Applications , Luana Mazzarella * y, Anna B. Morales-Vilches , Lars Korte, Rutger Schlatmann and Bernd Stannowski Helmholtz-Zentrum Berlin für Materialien und Energie, Schwarzschildstr. 3, 12489 Berlin, Germany; [email protected] (A.B.M.-V.); [email protected] (L.K.); [email protected] (R.S.); [email protected] (B.S.) * Correspondence: [email protected] Present address: Photovoltaic Materials and Devices Group, Delft University of Technology, 2628 CD Delft, y The Netherlands. Received: 17 July 2020; Accepted: 28 July 2020; Published: 3 August 2020 Abstract: Doped hydrogenated nanocrystalline (nc-Si:H) and silicon oxide (nc-SiOx:H) materials grown by plasma-enhanced chemical vapor deposition have favourable optoelectronic properties originated from their two-phase structure. This unique combination of qualities, initially, led to the development of thin-film Si solar cells allowing the fabrication of multijunction devices by tailoring the material bandgap. Furthermore, nanocrystalline silicon films can offer a better carrier transport and field-effect passivation than amorphous Si layers could do, and this can improve the carrier selectivity in silicon heterojunction (SHJ) solar cells. The reduced parasitic absorption, due to the lower absorption coefficient of nc-SiOx:H films in the relevant spectral range, leads to potential gain in short circuit current. In this work, we report on development and applications of hydrogenated nanocrystalline silicon oxide (nc-SiOx:H) from material to device level. We address the potential benefits and the challenges for a successful integration in SHJ solar cells.
    [Show full text]
  • SCIENCE BEHIND the NANO SOLAR CELL Kshitij Yograj Patil 1 , Dr
    SCIENCE BEHIND THE NANO SOLAR CELL Kshitij Yograj Patil 1 , Dr. Vishali P.Sonawane 2 , Yograj Gorakh Patil 3 1. Student in First year Engineering , Sapkal Knowledge Hub , Anjneri (NASIK). 2. Asstent prof in Engineering Chemistry ,Brahama Valley,Engg.College,Anjneri –(NASIK) 3.Siniour Executive Officer in Glenmark ABSTRACT The Global Warming is today’s major problem of the world. Nano-technology has to come as boon in the energy sources in the form of solar –cell. It is eco-friendly device Nanotechnology, with its unprecedented control over the structure of materials, can provide us with superior materials that will unlock tremendous potential of many energy technologies currently at the discovery phase. The quest for more sustainable energy technologies is not only a scientific endeavor that can inspire a whole generation of scientists, but the best way to establish a new economy based on innovation, better paid jobs, and care for the environment I. INTRODUCTION As we know that Sun shines approximately 1000 watts of energy per square kilometer of Earth. If all this energy is to be converted into usable forms then it can light up our homes for many centuries that also free of cost. So this energy was collected in the form of panels called as solar panels. Solar panels are effective way to channelize sunlight and use it for electricity. An array of solar panels are also used to convert solar energy into electrical energy. solar cell were of larger size and having efficiency of 67.4% but changing the panel by silicon nano rods made it possible to capture 96.7% of light.
    [Show full text]
  • Comparative Lifecycle Energy Payback Analysis of Multijunction Asige And
    PROGRESS IN PHOTOVOLTAICS: RESEARCH AND APPLICATIONS Prog. Photovolt: Res. Appl. 2011; 19:228–239 Published online 15 July 2010 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/pip.990 BROADER PERSPECTIVES Comparative life-cycle energy payback analysis of multi-junction a-SiGe and nanocrystalline/a-Si modules H.C. Kim1 and V.M. Fthenakis1,2* 1 Center for Life Cycle Analysis, Columbia University, NY, USA 2 Photovoltaic Environmental Research Center, Brookhaven National Laboratory, Upton, NY, USA ABSTRACT Despite the publicity of nanotechnologies in high tech industries including the photovoltaic sector, their life-cycle energy use and related environmental impacts are understood only to a limited degree as their production is mostly immature. We investigated the life-cycle energy implications of amorphous silicon (a-Si) PV designs using a nanocrystalline silicon (nc-Si) bottom layer in the context of a comparative, prospective life-cycle analysis framework. Three R&D options using nc-Si bottom layer were evaluated and compared to the current triple-junction a-Si design, i.e., a-Si/a-SiGe/a-SiGe. The life-cycle energy demand to deposit nc-Si was estimated from parametric analyses of film thickness, deposition rate, precursor gas usage, and power for generating gas plasma. We found that extended deposition time and increased gas usages associated to the relatively high thickness of nc-Si lead to a larger primary energy demand for the nc-Si bottom layer designs, than the current triple-junction a-Si. Assuming an 8% conversion efficiency, the energy payback time of those R&D designs will be 0.7–0.9 years, close to that of currently commercial triple-junction a-Si design, 0.8 years.
    [Show full text]
  • High Efficiency and High Rate Deposited Amorphous Silicon-Based Solar Cells”, NREL Phase I Annual Technical Progress Report (Sept
    A national laboratory of the U.S. Department of Energy Office of Energy Efficiency & Renewable Energy National Renewable Energy Laboratory Innovation for Our Energy Future Subcontract Report High Efficiency and High Rate NREL/SR-520-39091 Deposited Amorphous Silicon- January 2006 Based Solar Cells Final Technical Report 1 September 2001 – 6 March 2005 X. Deng University of Toledo Toledo, Ohio NREL is operated by Midwest Research Institute ● Battelle Contract No. DE-AC36-99-GO10337 High Efficiency and High Rate Subcontract Report NREL/SR-520-39091 Deposited Amorphous Silicon- January 2006 Based Solar Cells Final Technical Report 1 September 2001 – 6 March 2005 X. Deng University of Toledo Toledo, Ohio NREL Technical Monitor: Bolko von Roedern Prepared under Subcontract No. NDJ-2-30630-08 National Renewable Energy Laboratory 1617 Cole Boulevard, Golden, Colorado 80401-3393 303-275-3000 • www.nrel.gov Operated for the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy by Midwest Research Institute • Battelle Contract No. DE-AC36-99-GO10337 This publication was reproduced from the best available copy submitted by the subcontractor and received no editorial review at NREL. NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof.
    [Show full text]
  • High-Efficiency Amorphous Silicon and Nanocrystalline Silicon- DE-AC36-99-GO10337 Based Solar Cells and Modules: Final Technical Progress Report, 5B
    A national laboratory of the U.S. Department of Energy Office of Energy Efficiency & Renewable Energy National Renewable Energy Laboratory Innovation for Our Energy Future High-Efficiency Amorphous Subcontract Report NREL/SR-520-43191 Silicon and Nanocrystalline May 2008 Silicon-Based Solar Cells and Modules Final Technical Progress Report 30 January 2006 – 29 January 2008 S. Guha and J. Yang United Solar Ovonic LLC Troy, Michigan NREL is operated by Midwest Research Institute ● Battelle Contract No. DE-AC36-99-GO10337 High-Efficiency Amorphous Subcontract Report NREL/SR-520-43191 Silicon and Nanocrystalline May 2008 Silicon-Based Solar Cells and Modules Final Technical Progress Report 30 January 2006 – 29 January 2008 S. Guha and J. Yang United Solar Ovonic LLC Troy, Michigan NREL Technical Monitor: Bolko von Roedern Prepared under Subcontract No. ZXL-6-44205-14 National Renewable Energy Laboratory 1617 Cole Boulevard, Golden, Colorado 80401-3393 303-275-3000 • www.nrel.gov Operated for the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy by Midwest Research Institute • Battelle Contract No. DE-AC36-99-GO10337 This publication was reproduced from the best available copy Submitted by the subcontractor and received no editorial review at NREL NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights.
    [Show full text]
  • Strategies for Doped Nanocrystalline Silicon Integration in Silicon Heterojunction Solar Cells Johannes P
    1132 IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 6, NO. 5, SEPTEMBER 2016 Strategies for Doped Nanocrystalline Silicon Integration in Silicon Heterojunction Solar Cells Johannes P. Seif, Antoine Descoeudres, Gizem Nogay, Simon Hanni,¨ Silvia Martin de Nicolas, Niels Holm, Jonas Geissbuhler,¨ A¨ıcha Hessler-Wyser, Martial Duchamp, Rafal E. Dunin-Borkowski, Martin Ledinsky, Stefaan De Wolf, and Christophe Ballif Abstract—Carrier collection in silicon heterojunction (SHJ) so- (PECVD) features nanometer-sized silicon crystals embedded lar cells is usually achieved by doped amorphous silicon layers of in an amorphous silicon (a-Si:H) matrix. This material has al- a few nanometers, deposited at opposite sides of the crystalline sil- ready been studied for several decades and found its way into icon wafer. These layers are often defect-rich, resulting in modest doping efficiencies, parasitic optical absorption when applied at the several important applications including photovoltaic devices front of solar cells, and high contact resistivities with the adjacent [1]–[8], thin-film transistors [9], and microelectromechanical transparent electrodes. Their substitution by equally thin doped systems [10]. Significant effort was put on the experimental nanocrystalline silicon layers has often been argued to resolve [11]–[16] and theoretical [17] investigation of its growth pro- these drawbacks. However, low-temperature deposition of highly cess [4], [18], as well as its electrical [19]–[21] and optical crystalline doped layers of such thickness on amorphous surfaces demands sophisticated deposition engineering. In this paper, we properties [2], [15]. review and discuss different strategies to facilitate the nucleation In the case of solar cells, μc-Si:H was for a long time mainly of nanocrystalline silicon layers and assess their compatibility with used as absorbing material of the bottom cell in so-called mi- SHJ solar cell fabrication.
    [Show full text]
  • Nanocrystalline Silicon Thin Film Growth and Application
    Nanoscale Advances View Article Online REVIEW View Journal | View Issue Nanocrystalline silicon thin film growth and application for silicon heterojunction solar cells: Cite this: Nanoscale Adv.,2021,3,3373 a short review Mansi Sharma, * Jagannath Panigrahi and Vamsi K. Komarala Doped nanocrystalline silicon (nc-Si:H) thin films offer improved carrier transport characteristics and reduced parasitic absorption compared to amorphous silicon (a-Si:H) films for silicon heterojunction (SHJ) solar cell application. In this article, we review the growth conditions of nc-Si:H thin films as the carrier-selective layers for SHJ solar cells. Surface and growth zone models are analysed at different stages of incubation, nucleation, and growth of the silicon nanocrystallites within the hydrogenated Received 24th September 2020 amorphous silicon matrix. The recent developments in the implementation of nc-Si:H films and oxygen- Accepted 18th April 2021 alloyed nc-SiOx:H films for SHJ cells are highlighted. Furthermore, hydrogen and carbon dioxide plasma DOI: 10.1039/d0na00791a treatments are emphasised as the critical process modification steps for augmenting the nc-Si:H films' Creative Commons Attribution 3.0 Unported Licence. rsc.li/nanoscale-advances optoelectronic properties to enhance the SHJ device performance with better carrier-selective interfaces. 1. Introduction otherwise) mismatch among c-Si (n 3.8), a-Si (n 4.0), and the transparent conducting oxide (TCO) (n 2.0) at the front which Solar photovoltaics (SPV) is one of the best options to meet the may result in some optical reection losses.8 Moreover, the world's terawatt power demand in the near future.1 Silicon- highly defective a-Si:H(p) layer has slightly inferior electronic 9 s À2 À1 wafer based solar cells with high power conversion efficiency properties, e.g.
    [Show full text]
  • Hydrogenated Nanocrystalline Silicon P-Layer in A-Si:H Nip Solar Cells Wenhui Du , Xianbo Liao , Xieshen Yang, Henry Povolny
    Hydrogenated Nanocrystalline Silicon p-Layer in a-Si:H n-i-p Solar Cells Wenhui Dua), Xianbo Liaob), Xieshen Yang, Henry Povolny, Xianbi Xiangb), Xunming Deng Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA K. Sun Electron Microbeam Analysis Laboratory, University of Michigan, Ann Arbor, MI 48109, USA This paper investigates the impacts of hydrogenated nanocrystalline silicon (nc-Si:H) p-layer on the photovoltaic parameters, especially the open circuit voltage (Voc) of n-i-p type hydrogenated amorphous silicon (a-Si:H) solar cells. Raman scattering spectroscopy and transmission electron microscopy (TEM) analyses indicate that this p-layer is a diphasic material that contains nanocrystalline grains with size around 3-5 nm embedded in an amorphous silicon matrix. Optical transmission measurements show that the nc-Si p- layer has a wide bandgap of 1.96 eV, due to the quantum confinement effects (QCE). Using this kind of p-layer in n-i-p a-Si:H solar cells, the cell performances were improved with a Voc of 1.042 V, while the solar cell deposited under a similar condition but incorporating a hydrogenated microcrystalline silicon (µc-Si:H) p-layer leads to a Voc of 0.526 V. PACS: 73.63.Bd, 84.60.Jt a) Electronic mail: [email protected] b) Permanent address: Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 The limiting factors of open circuit voltage of a-Si:H solar cells have been an interesting topic since a-Si:H alloys became a viable material for photovoltaic devices. Theoretical considerations expected that recombination originating from band tail states puts a fundamental limit on the output voltage of p-i-n a-Si:H solar cells, and the maximum Voc calculated from the difference between the electron and hole quasi-Fermi levels in the intrinsic (i) layer is 1.0 ± 0.1 V.1 Experimentally, using high hydrogen dilution or hydrogen-plasma treatment, a-Si:H solar cells with Voc greater than 1.0 V could be fabricated,2,3 which is well consistent with the above theoretical estimation.
    [Show full text]
  • Alternative Designs for Nanocrystalline Silicon Solar Cells Atul Madhavan Iowa State University
    Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2009 Alternative designs for nanocrystalline silicon solar cells Atul Madhavan Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Electrical and Computer Engineering Commons Recommended Citation Madhavan, Atul, "Alternative designs for nanocrystalline silicon solar cells" (2009). Graduate Theses and Dissertations. 10487. https://lib.dr.iastate.edu/etd/10487 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Alternative designs for nanocrystalline silicon solar cells by Atul Madhavan A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Electrical Engineering Program of Study Committee: Vikram Dalal, Major Professor Rana Biswas Kristen Constant Joseph Shinar Arun Somani Iowa State University Ames, Iowa 2009 Copyright c Atul Madhavan, 2009. All rights reserved. ii TABLE OF CONTENTS LIST OF FIGURES . vii ACKNOWLEDGEMENTS . xvi ABSTRACT . xviii CHAPTER 1. INTRODUCTION . 1 1.1 Motivation . 1 1.2 Fundamentals of Solar cells . 2 1.3 Solar cell technologies . 3 1.3.0.1 Crystalline Silicon solar cells . 3 1.3.1 Thin film technologies . 4 1.3.1.1 Amorphous silicon alloys . 5 1.3.1.2 Micro/Nanocrystalline silicon . 5 1.3.1.3 CdTe and Cu2S....................... 6 1.3.1.4 Third and Fourth Generation Photovoltaics .
    [Show full text]