Highly reflective porous SiC with layered nanostructures formed by electrochemical etching

• Distinct layered nanostructures are achieved by electrochemical etching with a low concentration of HF. • Surface chemistry is studied via XPS for a comprehensive understanding of etching mechanisms. • As prepared spontaneously formed layered structures show an ultra-high optical reflectance for most of visible light. • The enhancement of reflectance is provided by the layered structures of SiC and air. A highly reflective porous SiC morphology having spontaneously layered nanostructures is described. It exhibits high reflectance (R > 90 %) across most of the visible light range. Fabrication is achieved by anodic electrochemical etching with a hydrofluoric acid /ethanol solution. The observed morphology demonstrates the ability of dilute HF to form distinctive layered nanostructures. A computer modelled multilayer interference effect is able to explain the observed high reflectivity. In addition, a comprehensive understanding of the etching mechanism was constructed based on the study of surface chemistry by X-ray photoelectron spectroscopy. Verification of the size effect was achieved by Raman spectroscopy and by X-ray diffraction. The measurement of fluorescent properties with photoluminescence and cathodoluminescence is also reported. The achievement of this thermally stable SiC reflector has potential applications in optoelectronics and sensors.