With the development of infrared detector technology, the demand for high-quality mercury cadmium telluride epitaxial materials is gradually increasing, which also puts forward higher requirements for the quality of cadmium zinc telluride substrates. The morphology and composition of a large-sized point like defect with a platform around it on the surface of a liquid-phase epitaxial cadmium telluride mercury film are characterized. The morphology of this type of defect is similar to a crater with a central depression (referred to as a “crater” shape), and its composition does not show significant deviation from the normal area of the tellurium cadmium mercury epitaxial film. Research has found that during the liquid-phase epitaxy process, approximately triangular or circular defects appear on the substrate surface before the growth solution of mercury cadmium telluride comes into contact with the cadmium zinc telluride substrate, and there are pore like morphologies below the defects. A “crater” shaped defect appears on the surface of the epitaxially grown mercury cadmium telluride film above the defect. The source of this defect is located to provide support for controlling the occurrence of such defects in the future.