黑硅的纳米结构可以大大降低硅表面的入射光反射率,同时由于比表面积的增加使其钝化成为难题,从而影响其太阳电池的性能。等离子体增强原子层沉积(PEAID)法沉积的Al2O3钝化层具有良好的保型性和致密性,适用于黑硅纳米微结构的钝化。本文使用金属辅助化学法制备多晶黑硅,再经低浓度碱溶液处理优化黑硅结构,最后用PEALD沉积了不同厚度的Al2O3钝化层。采用扫描电镜、分光光度计和少子寿命测试仪对黑硅的表面形貌、减反射特性和少子寿命变化进行了分析。结果表明碱溶液处理后黑硅表面结构变得更为平滑,Al2O3钝化的黑硅经退火后少子寿命达到8.96μs,在可见光范围内反射率降低至3.7%,与传统制绒工艺的多晶硅片相比性能有明显提升。
A novel technique was developed to passivate the surfaces of polycrystalline black silicon, a solar-cell ma- terial. First, black silicon was fabricated by metal-assisted chemical etching (MACE); next, its surface microstructures were modified by dipping into a dilute alkali solution; and finally, the modified surfaces were coated with an A1203 layer by plasma enhanced atomic layer deposition (PEALD). The impact of the A1203 growth conditions on the passivation was investigated. The nano-structures and minority carrier life-time of the passivated black silicon were characterized. The pre- liminary results show that the dipping into NaOH solution has a major impact on the properties of the passivated black sil- icon, possibly because of a reduced interface area. For instance, its minority carrier life-time increased up to 8.96 μs and its reflectance decreased to 3.7% in the visible range,much better than those of the texturized poly-silicon.