Synchrotron x-ray photoelectron spectroscopy study of hydrogen-terminated6H−SiC{0001}surfaces

Abstract

We report on highly resolved core-level and valence-band photoemission spectroscopies of hydrogenated, unreconstructed 6H-SiC(0001) and (0001 ) using synchrotron radiation. In the C 1s core level spectra of 6H-SiC(0001 ) a chemically shifted surface component due to C-H bonds is observed at a binding energy (0.47Ϯ0.02) eV higher than that of the bulk line. The Si 2p core-level spectra of SiC (0001) suggest the presence of a surface component as well but a clear identification is hindered by a large Gaussian width, which is present in all spectra and which is consistent with values found in the literature. The effect of thermal hydrogen desorption was studied. On 6H-SiC(0001) the desorption of hydrogen at 700-750°C is accompanied by a simultaneous transformation to the Si-rich (ͱ3ϫͱ3)R30°reconstruction. On 6H-SiC(0001 ) first signs of hydrogen desorption, i.e., the formation of a dangling bond state in the fundamental band gap of SiC, are seen at temperatures around 670°C while the (1ϫ1) periodicity is conserved. At 950°C a (3ϫ3) reconstruction is formed. The formation of these reconstructions on thermally hydrogenated 6H-SiC (0001) and (0001 ) is discussed in the light of earlier studies of 6H-SiC͕0001͖ surfaces. It will be shown that by using the hydrogenated surfaces as a starting point it is possible to gain insight into how the (ͱ3ϫͱ3)R30°and (3ϫ3) reconstructions are formed on 6H-SiC(0001) and 6H-SiC(0001 ), respectively. This is due to the fact that only hydrogen-terminated 6H-SiC͕0001͖ surfaces possess a surface carbon to silicon ratio of 1:1.

Substrate-dependent wetting layer formation during GaN growth: Impact on the morphology of the films

“…There are arguments, that may be some 30% smaller than given by the TPP calculations. 46 Nevertheless, the obtained value corresponds very well to the fact that all the Ga is laterally distributed in the topmost layer of the sample. After Ga metal deposition both the Ga 2p 3/2 and Ga 3d peak intensities increase due to the additional Ga on the surface but they remain significantly smaller than 1.…”

Silicon intercalation into the graphene-SiC interface

“…We have fit the spectra with a spin orbit split Si 2p peak (S2) and a second peak at higher binding energy (HBE) we associate with a SiC shifted surface state similar to the one observed for the clean SiC (3×3) surface. 13 The HBE peak forms after the first anneal and remains after further deposit and anneal cycles. When 1.4 ML of Si is evaporated at room temperature onto the 2 ML graphene, the Si 2p peak is larger and shifted 1.4eV to lower Binding Energy (BE).…”

Bottom–Up Fabrication of Carbon‐Rich Silicon Carbide Nanowires by Manipulation of Nanometer‐Sized Ethanol Menisci

“…The binding energies of the components are 284.8, 284.1, and 283.4 eV. Those components can be assigned to C±C sp 2 orbitals such as those in graphite, hydrogenated SiC [25] (Si 3 C±H environment), and SiC, [26,27] respectively. The formation of SiC and the incorporation of hydrogen in the compound is also supported by the study of the core-levelshifted components of the Si 2p photoemission peak (not shown).…”