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HL: Fachverband Halbleiterphysik

HL 9: SiC

HL 9.5: Vortrag

Montag, 22. März 2010, 12:30–12:45, H13

Electrical and Chemical Passivation of SiC Surfaces by Halogen Termination — •Sebastian Schoell, Marco Hoeb, Marianne Auernhammer, John Howgate, Martin S. Brandt, Martin Stutzmann, and Ian D. Sharp — Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, D-85748 Garching

Despite the technological maturity of SiC, few methods of chemical and electronic passivation of its surfaces are available. Treatment of SiC with HF yields OH-terminated surfaces with high defect densities. Here, we demonstrate plasma processing methods which yield F- and Cl-terminated (0001) 6H-SiC surfaces. X-ray photoelectron spectroscopy (XPS) reveals a significant reduction of oxygen, and corresponding increase of F- or Cl-core level intensities, following halogen termination. XPS core level shifts are consistent with surface photovoltage (SPV) measurements which show approximately flat band surface potentials (< 50 meV). Temperature programmed desorption (TPD) was performed and exhibited sharp peaks above 600 °C, indicating covalent surface termination rather than sub-surface incorporation of F and Cl. Measurements of both XPS and SPV as a function of ambient exposure time reveal slow oxidation with the magnitude of surface band bending increasing with time constants of approximately 40 hrs. Thus, halogen termination of SiC provides a practical method for both electronic and chemical passivation which has the potential to improve existing technological processes. Furthermore, this work offers the possibility for formation of self-assembled organic monolayers based on fluorine and chlorine chemistry.