Patterned SiC/Si heterostructures have been treated by anodic etching in HF/ethanol solutions at 25°C. The anodic process used a current density ranging from 2-10 mA/cm2 and times from 2-5 min. The SiC/Si samples had SiC regions and exposed Si regions of dimensions from 2.5 μm to ∼500 gm. For μm substrates, short etching times (≥3 min) result in selectivcarea UV-induced visible photoluminescence (PL) being observed at 25°C from only the SiC regions. Longer etching times (≥3 min) render both the SiC-protected and the exposed Si regions photoluminescent, with nearly identical spectral characteristics and with a peak located at 660-670 nm. The selective-area PL is based on the rapid lateral etching of the n-Si surface under the SiC layer due to either high surface stress caused by the lattice mismatch between SiC and Si and/or to a higher SiC conductance. This is confirmed by the time progression of the PL images in the SiC regions. The PL degradation with UV exposure time has been shown to be substantially reduced by a passivation procedure involving HNO3/H2O. For SiC/p-Si structures, the exposed Si regions become photoluminescent upon very short anodization time, while the SiC regions did not luminesce at all for even the longest anodization times used (5 min).