Morphological Instability of 4H-SiC (0001) Basal Plane Surface during Si-Vapor Thermal Etching

Abstract

The morphological instability appeared at step-free 4H-SiC (0001) surfaces was investigated. The step-free surfaces were fabricated at the bottom of inverted-mesa structure by the method combining a laser digging and Si-vapor etching. By repeated Si-vapor etching treatments, randomly created crater and maze structures were cyclically appeared at the step-free surfaces. These structures were distinctly classifiable by their depths from the step-free surfaces. Crater structures have 0.2 - 0.3 nm depth and maze structures have 0.5 nm depth. The morphological evolutions indicate the process of destruction of the step-free (0001) basal plane and generation of steps from step-free surfaces in the Si-vapor etching process.

Direct Observation of the Edge Termination of Surface Steps on 4H/6H-SiC {0001} by Tilted Low-Voltage Scanning Electron Microscopy

“…In this study, in order to relate the stacking orientation (surface termination) with the observed contrast, the comparison of the AFM images and the SEM images obtained at the identical positions is necessary. For this reason, inverted-mesa structures were fabricated via laser digging and the subsequent Si-vapor thermal etching at 1900-2100 o C [3,4]. At the bottom of the inverted-mesa structure, the surface having threading dislocations (TDs) was dominated by a particular step dynamics depending on either threading edge (TED) or screw (TSD) dislocation type.…”