| الوصف: |
This work focuses on characterizing the electronic structure and identifying reactions at interfaces, surfaces, and the heterostructures formed by deposition of Ga and Al on 90 nm of SiC deposited on Si(111) to understand the quality of the atomic interfaces, particularly important in the passivation process. For that purpose, the deposition processes and all steps of grown systems are followed in situ by high-resolution surface-sensitive synchrotron photoelectron spectroscopy, allowing different photon energies for core-level studies. The sample SiC/Si was produced by the method of atom substitution in a different experimental setup. Previously to any deposition, the SiC/Si itself needs to be characterized in detail, which was done using XPS and synchrotron photoelectron spectroscopy. The characterization of 3C-SiC(111) without any treatment, after depositions, annealing treatments and sputtering were made. All experiments were done and carried out previously. In this work fitting models are defined to analyze core level spectra (around 200 spectra were analyzed). The models are applied to the Si 2p, C 1s, O 1s, Si 2s, Al 2p, Ga 3d for different system conditions and chemical reactions. Chapter 2 provides a brief history of the photoelectron spectroscopy (PES) phenomena for XPS and Synchrotron, typical instrumentation, and the main spectral feature present in PES spectra. Chapter 3 describes the SiC system. Chapter 4 presents a brief experimental description of how the XPS, and Synchrotron results were obtained. This chapter informs the reader about the experimental conditions that lead to the analyzed core-level spectra. Chapter 5 focuses on spectral analysis peculiarities and the developed models. Chapter 6 results and discussion are presented. Film thickness is estimated using the Tougaard algorithm with different inelastic mean free paths calculated with NIST Electron Inelastic-Mean-Free-Path Database and compared with a common attenuation model. Sputtering effects are studied using the equivalent width and TRIM (TRANSPORT OF IONS IN MATTER) simulation. Peak fitting is employed to investigate chemical bonding in SiC and understand the effects of sputtering. The native oxide film thickness is calculated. Bandgap estimation of the thin oxide is performed using the energy loss region in the O 1s spectra. Synchrotron spectra are analyzed and fitted after Al and Ga depositions to investigate the formed chemical bonds. Stoichiometric Al-O bonds are formed. Aluminum silicates at the interface lead to graphene-like layers at low temperatures. Gallium deposition leads to the formation of Gallium oxidation states and islands.In Chapter 7, conclusions and perspectives are presented. My contribution in this work refers to all the mentioned work except experimental realization. |
