Efectes estructurals en les prestacions de contactes 2d metall/semiconductor i dispositius rram: estudis de primers principis i dinàmica molecular
- Autores: Maria Laura Urquiza Toledo
- Directores de la Tesis: Xavier Cartoixà Soler (dir. tes.)
- Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2020
- Idioma: español
- Tribunal Calificador de la Tesis: Stephan Roche (presid.), Riccardo Rurali (secret.), Nicolas Christophe Orlando Onofrio (voc.)
- Programa de doctorado: Programa de Doctorado en Ingeniería Electrónica y de Telecomunicación por la Universidad Autónoma de Barcelona
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
In this theis, finite bias transport properties of 2D MoS2 lateral metal-semiconductor junctions were studied through non-equilibrium Green’s functions calculations, aimed at contacting the 2D channel in a field effect transistor. The obtained results contributed to the understanding of the electrostatics in 2D junctions. Besides, the evaluation of different interface geometries allowed to predict the conditions that provide better contacting properties. From these studies, we contributed with an improved procedure to determine, experimentally or theoretically, emission regimes in 2D metal-semiconducting junctions.
Also, HfO 2 -based RRAM cells were studied using MD simulations with an extended charge equilibration method to describe external electric fields, which allowed to characterize the forming, reset and set processes. The analysis of the migration of oxygen ions and the change in the coordination of Hf atoms in the dielectric was used to describe the formation and dissolution of conductive filaments during the operation of the device with unprecedented detail. These studies were completed with DFT calculations of formation energies and activation barriers for the migration of oxygen vacancies, also obtained under the effect of an external electric field. In order to achieve such purpose, a novel scheme to perform calculations of slabs including a net charge and an electric field was proposed.
Finally, resistive switching phenomena in MoS 2 monolayers sandwiched between Au electrodes was studied through DFT transport calculations, with the intent to elucidate the structure responsable for the high and low resistance states.
