Combined Transmission Electron Microscopy and In-Situ Scanning Tunneling Microscopy Characterization of Nanomaterials
[eng] The main goal of this thesis has been to apply in-situ Transmission Electron Microscopy (TEM) electrical measurements using a Scanning Tunneling Microscopy (STM) tip, combined with TEM imaging and spectroscopic techniques, in order to address the characterization of relevant nanomaterials. Thi...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2018 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/125322 |
| Acceso en línea: | https://hdl.handle.net/2445/125322 http://hdl.handle.net/10803/663184 |
| Access Level: | acceso abierto |
| Palabra clave: | Microscòpia electrònica de transmissió Microscòpia d'efecte túnel Mesuraments elèctrics Materials nanoestructurats Transmission electron microscopy Scanning tunneling microscopy Electric measurements Nanostructured materials |
| Sumario: | [eng] The main goal of this thesis has been to apply in-situ Transmission Electron Microscopy (TEM) electrical measurements using a Scanning Tunneling Microscopy (STM) tip, combined with TEM imaging and spectroscopic techniques, in order to address the characterization of relevant nanomaterials. This system has not only been used to measure electrical properties, but also to carry out in-situ experiments with Joule heating and to apply mechanical stresses. A review of the different in-situ TEM techniques, their development over the years and their impact in the scientific community has been presented. Moreover, the instrumental used in this thesis, in particular, the TEM-STM system, has been described. In addition, two techniques for the preparation of specific samples for in-situ TEM-STM experiments have been presented: for nanostructured samples (2D materials, nanowires, etc), and for localized samples (devices, thin layers, bulk samples, etc). A gridcase that allows the use of conventional TEM grids in the TEM-STM system has been designed and fabricated in the context of this thesis. The use of this homemade gridase has allowed us to improve the experiments, offering more reproducibility and versatility. Finally, the calibration of the electrical measurements of the system has been carried out. Using the TEM-STM system, different type of nanostructures have been characterized during the present thesis, from 2D nanostructures, as the elucidation of the effects of electrical current through a single graphene oxide sheet, to functional devices, as the study of the ferroelectric and piezoelectric behavior of structures based on La2WO6, the study of the anisotropic electrical conductivity of GaInP CuPtB type ordering layers used for multijunction solar cells or the study of the conductive filament (CF) formation mechanism in three different Resistive random-access memory (ReRAM) devices. In summary, in-situ microscopy expands the horizons of the characterization and study of materials and, in particular, in the context of this thesis, an in-situ TEM-STM system has been used to electrically characterize samples from nanomaterials to functional devices. |
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