The EL tester applies a 1-40mA forward current to the battery slice and acts on both sides of the diffusion junction. The electric energy excites the atoms in the ground state to make them in the excited state. The atoms in the excited state are unstable and emit spontaneously. To understand the intrinsic transitions in spontaneous radiation through the function of the filter and the exposure level of the film, and to determine whether there are defects in the silicon film based on the relationship between minority carrier lifetime, density, and light intensity through the exposure level of the film. keywords：