In an example implementation, a method includes illuminating a wafer with excitation light having a wavelength and intensity sufficient to induce photoluminescence in the wafer. The method also includes detecting photoluminescence emitted from a portion of the wafer in response to the illumination, and detecting excitation light reflected from the portion of the wafer. The method also includes comparing the photoluminescence emitted from the portion of the wafer and the excitation light reflected from the portion of the wafer, and identifying one or more defects in the wafer based on the comparison.