Structural and electronic characterization on energy-related materials using TEM [electronic resource]
Keywords: Materials Science and Engineering.

The world's growing energy needs will involve not one but a harmonious collection of extremely efficient energy technologies that will work in concert to produce, store, and use the large amounts of energy that humans will soon demand. To provide a scientific establishment for break-out high-efficiency, cost-effective energy technologies, research activities have been focused on manipulation of materials at the nanometer scale to increase efficiency of energy conversion devices and exploitation of fundamental advances in charge transport, light absorption, and reaction thermodynamics and kinetics to improve performance and efficiency in energy conversion devices like solar cell, fuel cell, and photoelectrochemical (PEC) cell. To achieve these goals, we need to understand how nano-structuring modifies and governs the properties of materials, and how to control dimensionality and confinement to learn insights on model energy conversion materials, structures and devices. Transmission Electron Microscopy (TEM) with additional advanced functions enables us to approach profound understanding of the fundamental relationship between chemical / electronic / optical properties of materials and origin (crystal structure, composition, size, shape) of them through the characterization at atomic or nano/micro scale. This dissertation will mainly deal with the TEM characterization on the energy-related materials for the solar cell and fuel cell (especially, solid oxide fuel cell) using a variety of different TEM techniques. The most of sample was prepared by conventional TEM preparation method or site-specific lift-out technique using a focused ion beam (FIB). Subsequent TEM studies on these energy-related materials lead to have deep understanding of the relationship between the atomic scale structures with the other chemical/optical/electronic property. In the chapter 1, the brief concept and background of the solar cell and fuel cell will be included. In the chapter 2, the details of TEM/STEM background for imaging and diffraction with a variety of additional TEM spectroscopic techniques like X-ray energy dispersive (EDS) and electron energy loss spectroscopy (EELS) are included because this dissertation is mainly focused on TEM characterization. And the background of FIB/SEM and sample preparation using FIB is followed. In the chapter 3, the TEM characterization on the diverse kinds of materials of the 2nd and 3rd generation solar cells mainly made by atomic layer deposition (ALD) is dealt with using different types of spectroscopic techniques. ZnS, CdS, ZnxCd1-xS, PbS deposited by ALD for the 2nd and 3rd generation solar cell and the advanced bottom electrode structure are included. Each sub-chapter in the chapter 3 is based on the published papers as follows: Chapter 3-2: "Atomic layer deposition of ZnS via in situ production of H2S", J.R. Bakke, J.S. King, H.J. Jung, R. Sinclair, S.F. Bent, Thin Solid Films. 518. pp. 5400-5408 (2010). Chapter 3-3: "Atomic Layer Deposition of CdS Films", Jonathan R. Bakke, Hee Joon Jung, Jukka T. Tanskanen, Robert Sinclair, and Stacey F. Bent, Chem. Mater. 22, 4669-4678 (2010). Chapter 3-4: "Atomic Layer Deposition of CdxZn1-xS Films", Jonathan. R. Bakke, Jukka T. Tanskanen , Hee Joon Jung, Robert Sinclair, Stacey F. Bent, J. Mater. Chem., 21, 743-751 (2011). Chapter 3-5: "Scanning Tunneling Spectroscopy of Lead Sulfide Quantum Wells Fabricated by Atomic Layer Deposition for Band Gap Engineering", Wonyoung Lee, Neil P. Dasgupta, Hee Joon Jung, Jung-Rok Lee, Robert Sinclair and Fritz B. Prinz, Nanotechnology, 21, 485402, 4pp. (2010). Chapter 3-6: "Atomic Layer Deposition of Lead Sulfide Quantum Dots on Nanowire Surfaces", Hee Joon Jung, Neil Dasgupta, Orlando Trejo, Matthew T. McDowell, Aaron Hryciw, Mark Brongersma, Robert Sinclair and Fritz B. Prinz, Nano Lett., 11 (3), pp 934-940 (2011). Chapter 3-7: "Evidence For Shape-Induced Bandgap Variations Within a Single Quantum Dot", Hee Joon Jung, Neil P. Dasgupta, Philip B. Van Stockum, Ai Leen Koh, Robert Sinclair, Nature Nanotehchnol., (2012) under review. Chapter 3-8: "Nickel Silicide Nanowire Arrays for Anti-Reflective Electrodes in Photovoltaics", Neil P. Dasgupta, Shicheng Xu, Hee Joon Jung, Andrei Iancu, Rainer Fasching, Robert Sinclair, Fritz B. Prinz, Adv. Funct. Mater., Vol. 22, Issue 17, 3650-3657 (2012). In chapter 4, the TEM characterization on the materials of the solid oxide fuel cells which Yttrium-doped Barium Zirconate (BYZ) by the atomic layer deposition (ALD) and Gadolinia (Ge2O3)-doped Ceria (CeO2) by the pulsed laser deposition (PLD) is dealt with. Each sub-chapter in the chapter 4 is based on the published papers as follows: Chapter 4-2: "Effect of crystallinity on ionic conductivity of Y-doped Barium Zirconate", Y.B. Kim, T.M. Gur, H.J. Jung, S. Kang, R. Sinclair, F.B. Prinz, Solid State Ionics, Vol. 198, Issue 1, 19, 39-46 (2011). Chapter 4-3: "Oxygen Surface Exchange at Grain Boundaries of Oxide Ion Conductors", Wonyoung Lee, Hee Joon Jung, Min Hwan Lee, Young-Beom Kim, Joong Sun Park, Robert Sinclair, and Fritz B. Prinz, Adv. Funct. Mater., Vol. 22, Issue 5, 965--971 (2012).