Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 35: Poster Session I (Metal, semiconductor and oxide substrates: structure and adsorbates; Graphene)

O 35.42: Poster

Dienstag, 12. März 2013, 18:15–21:45, Poster B1

Improving the Quality of SiC Surfaces by Precise Definition of H2-Etching Parameters — •Tobias Denig and Ulrich Starke — Max-Planck-Institut für Festkörperforschung, D-70569 Stuttgart Germany

SiC is a material of great technical interest because it offers an attractive combination of chemical robustness and excellent thermal and electrical properties. However, in order to make use of these characteristics one needs a well-behaved, passivated surface. This has led to the prevalence of a H2 etching step in SiC processing, as it simultaneously removes surface damage (e.g., polishing scratches), reduces the defect density, and leaves behind an "atomically-flat," H-terminated terraced surface. In the ideal limit, such steps should be one SiC bilayer (0,25 nm) thick. A common occurrence in such etching is for two or more steps to bunch, producing steps of one or several unit cell heights. The end result is a mixture of step heights, producing a sub-optimal surface for further work. However, one unit cell height should be a natural step size due to the particular stacking order in SiC polytypes. Various etch parameters (gas flowrate, T, and p) can influence the amount of step bunching. We have performed parameterization studies aimed at limiting this process such that only steps of (single) unit cell height emerge. All samples used in these studies underwent a modified RCA clean prior to being etched. The results of varying the processing conditions as well as using Ar or H2 as the cooling gas were examined using XPS, LEED, and AFM.