Passivating layer of solar cell and preparing process of passivating layer

The invention discloses a passivating layer of a solar cell and a preparing process of the passivating layer. The passivating layer is characterized by being formed by Gd2O3. The preparing process comprises the steps of firstly depositing a Gd2O3 passivating layer at the P-type side of a P-type or N-type crystal silicon wafer with an atom layer deposition method, then performing annealing treatment to form an SiO2 buffer layer between the passivating layer and the P-type side of the P-type or N-type crystal silicon substrate, thus finishing the preparing of the passivating layer. The passivating layer is good in lattice matching, has the dual actions of the field effect passivating and the chemical passivating, and is good in passivating effect. The passivating layer crystal structure obtained by adopting the preparing process is integral in structure, low in defect density and good in lattice matching with the crystal silicon substrate, and the passivating effect of the cell is ensured.