Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 50: Semiconductor Substrates: Structure, Epitaxy, Growth and Adsorption

O 50.2: Poster

Dienstag, 21. März 2017, 18:30–20:30, P1A

Hydrogen etching of SiC(0001): Route to an epitaxy template — •Maximilian Bauernfeind, Felix Reis, Victor Rogalev, Marius Will, Ralph Claessen, and Jörg Schäfer — Physikalisches Institut and Röntgen Center of Complex Material Systems (RCCM), Universität Würzburg, 97074 Würzburg, Germany

The hexagonal (0001) surface of silicon carbide offers a huge playground for the epitaxy of a variety of different materials. An intriguing aspect is the growth of honeycomb lattices made of high-Z elements, such as Sn or Bi, predicted to exhibit topological protected edge states. To enable successful epitaxy of such materials, one has to focus on the substrate quality, and prepare defect-free and well-ordered flat surfaces. In-situ gas phase etching in a hydrogen atmosphere makes it possible to achieve these required qualities.

Here we demonstrate the effects of different etching parameters studied by scanning tunneling microscopy. The results are analyzed regarding large-scale terrace formation and defect density. In general, the etched substrate surface becomes hydrogen-passivated which, however, impedes the bonding of the admitted high-Z atoms. One approach to hydrogen desorption from SiC(0001) discussed in the literature is a photoinduced process with synchrotron UV light.

In addition, we present the succesful thermal desorption of hydrogen and the formation of a dangling bond (DB) state, as inspected by photoemission. The surface density of the DB state is analyzed in an annealing study. This finally renders SiC as a versatile growth template.