体缺陷主导的少子寿命衰减:光伏用n型Cz硅片高温行为机理与抑制策略OA

The minority carrier lifetime of silicon wafers generally decays sharply after high-temperature processes in solar cell fabrication,significantly limiting further improvements in cell efficiency.To elucidate the underlying mechanism,this study systematically investigated the high-temperature behavior of photovoltaic-grade n-type Czochralski(Cz)silicon wafers through controlled heat treatment experiments,combined with multi-scale characterization techniques including minority carrier lifetime,photoluminescence(PL),and Fourier-transform infrared spectroscopy.The results demonstrate that the significant degradation in both minority carrier lifetime and PL intensity after high-temperature treatment primarily stems from a substantial increase in bulk recombination defects,with surface conditions and process atmosphere playing a minor role.Furthermore,during heat treatment,interstitial oxygen within the silicon wafer converts into precipitated oxygen,accompanied by net inward diffusion of ambient oxygen in an oxygen-rich atmosphere.Comprehensive analysis indicates that oxygen precipitate nuclei pre-existing in the as-grown silicon wafers become activated and grow during high-temperature process,forming oxygen precipitates with high recombination activity,which is identified as the main cause of minority carrier lifetime degradation.Based on the mechanism of'selective activation and growth of oxygen precipitate nuclei',this study proposes two optimization strategies:suppressing nucleus formation by optimizing the crystal cooling thermal history and eliminating existing defects through rapid thermal annealing.