Dresden 2003 – wissenschaftliches Programm
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O: Oberflächenphysik
O 20: Halbleiteroberfl
ächen und -grenzfl
ächen
O 20.4: Vortrag
Dienstag, 25. März 2003, 15:45–16:00, FOE/ANOR
Preferential carbon etching by hydrogen in voids of 6H-SiC(1000) — •Wulf Wulfhekel1, D. Sander1, M. Hanbücken2, S. Nitsche2, J.P. Palmari2, F. Dulot2, and F.A. d Avitaya2 — 1MPI Halle, Weinberg 2, 06120 Halle — 2CRMC2, Campus de Lumini, 13288 Marseille
6H-SiC(0001) samples have been etched in a hot-wall reactor at a hydrogen pressure of 13 mbar at 1800∘C. The surface morphology and elemental composition have been studied by scanning electron microscopy and micro-Auger analysis. Stoichiometric etching of SiC is found on the flat sections of the surface, but in hexagonal voids, a selective removal of C, leading to a pure Si surface at the bottom of the voids, is observed. Fast gas diffusion is the main transport mechanism for etching of the flat surface, while Knudsen diffusion dominates inside the voids. It is proposed that the lower diffusion constant of reaction products containing Si compared to those containing C, leads to a preferential removal of C and a Si enrichment inside the voids.