A Study on Calculation Methods for Surface Traps in Si3N4 Under Different Y3+ Doping Concentrations

To optimize the surface insulation performance of silicon nitride ceramics, this paper investigates the calculation methods for surface trap characteristics under different doping conditions. Based on density functional theory (DFT) within first-principles calculations, a simulation model for Y3+-doped β-Si3N4 crystals was established. The electronic density of states under varying Y3+ doping concentrations was systematically analyzed. The results indicate that Y3+ doping introduces shallow and deep impurity peaks within the bandgap, with the shallow impurity peak density being the lowest at a 4% doping concentration. Higher doping concentrations lead to a significant increase in deep impurity peak values. To validate the accuracy of the calculation model, surface potential decay (SPD) experimental results were compared, showing strong agreement between the measured trap distributions and the simulation results. The correlation mechanism between the surface charge and trap properties of Si3N4 under different Y2O3 doping is obtained from the experimental and simulation results of surface charge density, and it is determined that the surface charge properties of Si3N4 under 4% Y2O3 doping are optimal. The proposed calculation model effectively predicts the surface charge behavior of doped Si3N4, providing reliable theoretical support for the design and performance optimization of ultra-high voltage insulating materials.