| Silicon Carbide is an important semiconductor for its high frequency, high voltage, high temperature, and radiation resistant properties. Currently, progress in SiC technology is limited by a fundamental understanding of the processes that occur at the surface and interface. Surface science plays a crucial role in elucidating these processes and measuring fundamental parameters that are used in theoretical calculations for SiC. 4H-SiC has been studied in this dissertation to determine this essential information.; This dissertation concerns the study of Re and Nb interactions on 4H-SiC. Atomic force microscopy (AFM) images were obtained at room temperature of as received crystals which showed a corrugated surface with approximately 10 Å vertical structures. Atomically clean surfaces were obtained by thermal treatment followed by Ar+ sputtering and annealing. The results showed three temperature ranges with different surface carbonization kinetics. The surface carbonization resulted from volatization of silicon from the surface as well as surface reconstructions.; Auger electron spectroscopy and secondary electron emission, via the crystal current (SEECC) method, were utilized to monitor the adsorption of rhenium and niobium on both basal surfaces of 4H-SiC. Adsorption of the metals on the surfaces were at room temperature (300 K) and interrupted for AES and SEECC measurements. The crystal current measurements are compared to the change in Auger electron spectroscopy peak to peak signal intensities for both the substrate and the adsorbate, to show that the growth mode was monolayer formation followed by simultaneous monolayers (MSM) for both metals on the 4H-SiC(0001) surface and layer by layer (Frank-van der Merwe, FM) growth on the 4H-SiC(0001¯) surface. The inelastic mean free path of the Si(LVV) 89.9 eV Auger electron in Re was found to be 2.4 ML on both surfaces and 3.3 ML in Nb on the Si face and 1.9 ML in Nb on the C face.; Formation of Schottky barrier contacts to three surfaces of n-type 4H-SiC were studied for three metals (Ni, Ti, and Nb) using the shift in the X-ray photoelectron spectroscopy (XPS) of the C(1s) peak of SiC. The C(1s) peak to valence band maximum for 4H-SiC(0001), 4H- SiC(0001¯), and 4H-SiC(0001), off axis 3.5° was determined to be 281.95, 281.85, and 282.08 eV respectively. The metals were deposited on room temperature crystals with a small native oxide layer and the metal films were less than three ML thick. |
