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Ferroelectric-Semiconductor Systems for New Generation of Solar Cells University of New Orleans ScholarWorks@UNO University of New Orleans Theses and Dissertations Dissertations and Theses Spring 5-19-2017 Ferroelectric-Semiconductor Systems for New Generation of Solar Cells Rahmatollah Eskandari University of New Orleans, New Orleans, [email protected] Follow this and additional works at: https://scholarworks.uno.edu/td Part of the Semiconductor and Optical Materials Commons Recommended Citation Eskandari, Rahmatollah, "Ferroelectric-Semiconductor Systems for New Generation of Solar Cells" (2017). University of New Orleans Theses and Dissertations. 2318. https://scholarworks.uno.edu/td/2318 This Dissertation is protected by copyright and/or related rights. It has been brought to you by ScholarWorks@UNO with permission from the rights-holder(s). You are free to use this Dissertation in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/ or on the work itself. This Dissertation has been accepted for inclusion in University of New Orleans Theses and Dissertations by an authorized administrator of ScholarWorks@UNO. For more information, please contact [email protected]. Ferroelectric-Semiconductor Systems for New Generation of Solar Cells A Dissertation Submitted to the Graduate Faculty of the University of New Orleans in partial fulfillment of the requirement for the degree of Doctor of Philosophy in Engineering and Applied Science (Physics) by Rahmatollah Eskandari M.Sc. University of Tabriz, Iran, 2006 B.Sc. Amirkabir University of Technology, Iran, 2002 May, 2017 Copyright 2017 Rahmatollah Eskandari ii To: My Family iii Acknowledgement I would like to express my heartfelt gratitude and appreciation to my advisor Prof. Leszek Malkinski who provided me the excellent opportunity to work and learn in his group. His kindness and patience provided a welcoming environment and his inspiring ideas created an exciting research while his knowledge, experience, and consistent help made the obstacles of the research easy. Thank you Dr. Malkinski. I am thankful to my committee members Prof. Leonard Spinu, Prof. Weilie Zhou, Prof. Ashok Puri, and Prof. Paul Schilling for their time and helpful suggestions and comments and for supporting my research by providing instruments and helpful advice anytime I needed. I am also grateful to the support from Profs. Kevin Stokes and John Wiley for clarification of many scientific and technical issues. I am also indebted Dr. Xiaodong Zhang from Tulane University for the XPS measurements. I would like to have this chance to appreciate my former and current group members Dr. Seong-Gi Min, John Gaffney, Ganesh Tiwari, Athanasios Chalastaras, Md Hasan, Atikur Rahman and Happyson Gavi for all the help and support I received from, especially Dr. Min for the training on various scientific instruments and introduction to a field that was little known to me. I would also like to acknowledge my friends in AMRI, Physics and Chemistry departments Dr. Taha Rostamzadeh, Dr. Satish Chandra Rai, Dr. Amin Yourdkhani, Ali Radmanesh, Shankar Khanal, Daniel Adams, Zhi Zheng, Shuke Yan, Dr. Sarah Wozny, Richie Provost, Sara Akbarian, Dr. Darius Montasserasadi, Dr. Parisa Pirani, and Dr. Saman Salemizadeh for the joyful time we shared together at UNO. I am also thankful to the present and past AMRI office staff Poncho De Leon, Jennifer Tickle, and Amanda Lamastus for all of their help in paperwork and purchasing as well as Dr. Charles G. Seab and Denise Bauer at Physics Department’s office for iv providing assistantships that was vital to me and for their help. I am also indebted to Harry J. Rees for troubleshooting and fixing of key instruments. Although no word can fully express my gratitude, my deepest appreciation goes to my wife Zahra Heidari, my father, mother, and my siblings for their never-ending support, patience, and love. I feel blessed to have you in my life and will be indebted forever for all the sacrifices you have made. Thank you. I would like to thank National Science Foundation for the support through the grant NSF EPSCoR LA-SiGMA Cooperative Agreement No. EPS-1003897, Louisiana Board of Regents Contract No NSF(2010-15)-RII-UNO and UNO for the support via SCORE 2012 grant. v Table of Contents Abstract ........................................................................................................................... ix Part I: Sputtered Si doped Hafnia: Synthesis, and Characterization of Ferroelectric and Photovoltaic Properties Chapter 1: .......................................................................................................................... 2 Photovoltaic Effect and Ferroelectricity, Theoretical Background .................................... 2 1.1 Introduction ................................................................................................................................... 2 1.2 Photovoltaic Theory ...................................................................................................................... 4 1.2.1 P-N Junction ............................................................................................................................. 5 1.2.2 Schottky Junction ..................................................................................................................... 8 1.2.3 Current-Voltage Characteristics and Efficiency ....................................................................... 8 1.2.4 Solar Cell Types ...................................................................................................................... 11 1.2.4.1 First Generation Solar Cells ......................................................................................... 11 1.2.4.2 Second Generation Solar Cells ...................................................................................... 12 1.2.4.3 Third Generation Solar Cells ........................................................................................ 13 1.2.4.4 New Generations of Solar Cells and Emerging Concepts ............................................. 14 1.3 Ferroelectricity ............................................................................................................................. 15 1.3.1 Hysteretic Behavior in Ferroelectrics ...................................................................................... 17 1.3.2 Applications of Ferroelectric Materials ................................................................................... 19 1.4 Photovoltaic Ferroelectrics .......................................................................................................... 19 1.5 Focus of the Study ....................................................................................................................... 21 References ............................................................................................................................................ 23 Chapter 2: ......................................................................................................................... 26 Synthesis of Ferroelectric HfO2 Thin Films ...................................................................... 26 2.1 Introduction ................................................................................................................................. 26 2.1.1 Ferroelectricity in HfO2 thin films .......................................................................................... 28 2.1.2 Crystal Structure of HfO2 ....................................................................................................... 29 2.1.3 Applications of HfO2 ............................................................................................................... 31 2.1.4 Synthesis Methods of Ferroelectric HfO2 ................................................................................ 32 2.2 Experimental ................................................................................................................................ 33 2.2.1 Sample Preparation and Deposition Conditions ..................................................................... 33 2.2.2 Rapid Thermal Annealing ...................................................................................................... 35 2.2.3 Electrode Preparation for Hysteresis Measurement ................................................................ 36 2.2.4 Characterization Methods ....................................................................................................... 38 2.2.4.1 Film Thickness ............................................................................................................. 38 2.2.4.2 Elemental Analysis ....................................................................................................... 38 2.2.4.3 Crystalline Structure .................................................................................................... 39 2.2.4.4 Ferroelectricity and Hysteresis ..................................................................................... 39 2.3 Results and Discussion ................................................................................................................. 41 2.3.1 XPS Results ............................................................................................................................ 41 vi 2.3.2 Phase
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