The photonic crystals (PCs) with defect layer containing negativeindex materials coated over a SiC substrate are investigated by a transfer matrix method. The results show that this coherent thermal radiation source has very sharp emissivity peaks within a narrow wavelength band at a welldefined direction; the quality factor of the emissivity peak is high. This emissivity peak is not sensitive to the emission angle, polarization, and scaling factor of the photonic crystals in the structure. The value, quality factor, and position of the emissivity peak can be effectively controlled by tuning the thickness and refraction index of the defect layer.