Investigation of the structure and stability of the Pt/SiC(001) interface

Abstract

Auger electron spectroscopy and low energy electron diffraction have been applied to the study of the structure and thermal stability of the Pt/j3-SiC(001) interface. The morphology of the interface appears to be governed by the competition among surface diffusion, intermixing, and chemical reaction. An ultrathin Pt layer (=S8 A thick) deposited on a substrate at low temperature is laterally uniform with some degree of intermixing across the interface. Brief anneals at =Sl000 °C result in aggregation of the Pt into islands interspersed with essentially bare SiC. Higher temperatures lead to reaction of the aggregated Pt to form Pt silicide and release free C. The reaction is signaled by characteristic changes in the Si LVV and C KLL Auger line shapes and by the appearance in LEED of a (2 x 2) pattern (believed to arise from ordered PtSi) and of diffraction rings from oriented polycrystalline graphite. Subsequent deposition of Si and annealing leads to regeneration of SiC by reaction with the free C. These results contrast with those for ultrathin Pt on Si(001) and on a-SiC(OOOl) which are dominated by the rapid indiffusion of Pt during annealing. A detailed model is presented for the growth and annealing dependence of the Pt/j6-SiC (001) interface. Downloaded: 13 Apr 2015 IP address: 169.230.243.252V. M. Bermudez and R. Kaplan: Investigation of the structure and stability of the Pt/SiC(001) interface

Surface morphology and electrical property evolution of super-thin Pt film on 6H-SiC substrate during annealing

“…Figure 2c represents the islands scattering on the surface of the sample annealed at 600 °C for 10 min. This result agrees with the work of Bermudez et al (1990), where Pt films (≤0.8 nm thick) were deposited on cubic β-SiC (001) surfaces, and also compatible with the case of a Pd film on a SiC substrate (Veuillen et al , 1999; Tsiaoussis et al , 2007). The reason for the island growth on a SiC single crystal substrate may come from crystal lattice mismatch at the interface and inhomogeneous stress induced by the thermal process of the Pt/SiC interface.…”

“…Pt can react with SiC to form Pt-silicides: Pt 3 Si, Pt 12 Si 5 , Pt 2 Si, Pt 6 Si 5 , and PtSi (Rijnders et al , 1997; Xu et al , 2008). Papanicolaou et al (1989) and Bourenane et al (2007) reported that Pt is used for the fabrication of a good Schottky contact with a SiC single-crystal substrate throughout the annealing sequence, and studies of interface electrical property of Pt/SiC joints revealed that the contact resistivity depends on annealing parameters, thickness of a Pt film and phases involved at the interfaces (Bermudez et al , 1990; Chen et al , 1994; Porter and Davis, 1995). An increase of Schottky barrier height (SBH) can be controlled from the grain growth and the film homogeneity at the surfaces.…”

Na/carbon-rich β-SiC(100) surface: Initial interface formation and metallization

“…A similar behavior has been also observed for the Co/6H-SiC and Pt/ ␤-SiC͑100͒ interfaces where free carbon is released after silicide formation. 12,18 Upon low oxygen exposures, we observe that the peak N/peak M intensity ratio decreases indicating the decrease of these carbon species present at the surface. This behavior is likely resulting from CO and/or CO 2 formation and desorption into the vacuum as previously reported for alkali metal ͑Rb͒ room temperature promoted oxidation of the ␤-SiC͑100͒ surface.…”

“…6,7 In contrast, the formation of metal/silicon carbide interfaces has been investigated for several systems with various metal adsorbates having very different properties and including transition metals, [8][9][10][11][12] aluminum, 13,14 full or almost full d-band metals. [15][16][17][18] However, in most of these studies, rather thick metal films were used in order to explore the thermal stability of metallic contacts. Room temperature metal/SiC reactive interface formation was found to take place for Au, Ni, Pd, Ti, W, Mo, and Ta while for Pt, Sn, Al, and Co a reaction took place only above room temperature.…”

“…Room temperature metal/SiC reactive interface formation was found to take place for Au, Ni, Pd, Ti, W, Mo, and Ta while for Pt, Sn, Al, and Co a reaction took place only above room temperature. [8][9][10][11][12][13][14][15][16][17][18] These reactions generally involve silicon or carbon atoms ͑and in some cases both͒, depending of the metal nature and the surface composition. Also of special interest, silicon carbide surface metallization was found to take place in the case of rather high metal coverages, in large excess of a monolayer.…”