Quality evaluation of homopetaxial 4H-SiC thin films by a Raman scattering study of forbidden modes

The crystal quality of a 4H-silicon carbide (4H-SiC) epitaxial layer is crucial to the development of high-performance 4H-SiC-based electronic power devices. However, the quality assessment of 4H-SiC homoepitaxial thin film is problematic because the same bulk material interferes with the probe of the epilayer. In this paper, we propose a simple and straightforward strategy to assess the quality of a homoepilayer using ultraviolet (UV) Raman spectroscopy (RS). Rather than focusing on the normally allowed modes, we shift our attention to the forbidden modes instead. We demonstrate that forbidden modes, which were usually ignored, are more sensitive to the crystalline imperfection and can be an effective quality probe. Our approach analyzes the crystal quality swiftly, without the need for the data fitting involved in the conventional method, and therefore makes the quality assessment much more efficient. The new method may also be applied to the other thin film materials. (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement