Dresden 2003 – scientific programme

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HL: Halbleiterphysik

HL 11: SiC I

HL 11.6: Talk

Monday, March 24, 2003, 16:30–16:45, BEY/154

Characterization of ALCVD-Al₂O₃ thin films on 6H-SiC(0001) — •K.Y. Gao¹, F. Ciobanu², Th. Seyller¹, L. Ley¹, G. Pensl², A. Taddich³, J.D. Riley³, and R.G.C. Leckey³ — ¹Institut für Technische Physik, Universität Erlangen-Nürnberg, Germany — ²Institut für Angewandte Physik, Universität Erlangen-Nürnberg, Germany — ³Department of Physics, La Trobe University, Australia

Atomic Layer CVD was used to grow Al₂O₃ films on H-terminated, OH-terminated, and oxide terminated (silicate adlayer) 6H-SiC(0001) surfaces. The growth and interface properties were studied by X-ray induced photoelectron spectroscopy (XPS) and ellipsometry. The dependence of the Al₂O₃ film thickness on the number of deposition cycles indicates a layer-by-layer growth mode with an incubation period at the beginning of the growth. Additional ellipsometric measurements of thick films revealed that the Al₂O₃ films had an index of refraction of n=1.66 and the average growth rate was 1.0 Å per cycle. The XPS data further suggest that there is no SiO_x interface layer formed on H-terminated 6H-SiC(0001). This is corroborated by surface sensitive XPS measurements using synchrotron radiation of ultrathin layers of Al₂O₃ on H-terminated SiC(0001). On the other hand there is a clear interface layer observable when the substrate surface is prepared using the hydrogen plasma. Admittance spectroscopy measurements showed that the density of interface traps (D_it) was the lowest on H-terminated 6H-SiC(0001) (ca. 5×10¹¹ cm⁻²eV⁻¹ at 0.1 eV below CBM) and highest on the oxide terminated surface (4×10¹² cm⁻²eV⁻¹ at 0.1 eV below CBM).