氢化非晶硅叠层薄膜对单晶硅表面钝化研究

采用等离子体增强化学气相沉积法生长的单层本征氢化非晶硅薄膜对单晶硅片进行钝化,结果表明增加氢稀释比有利于减少薄膜中的缺陷,增强钝化效果,过量的氢稀释比会导致非晶硅在硅片表面的外延晶化生长,降低钝化效果。退火导致非晶硅晶化程度增加,降低了钝化效果,同时退火提升了薄膜的质量,改变了H键合方式,增强了钝化效果。因此,单层氢化非晶硅只有在合适的氢稀释比和退火温度才可以获得最佳钝化效果。为了提高非晶硅薄膜对硅片的钝化效果,采用具有高低氢稀释比的叠层本征非晶硅薄膜对硅片进行钝化。因此将高氢稀释比沉积的非晶硅薄膜叠层生长于低氢稀释比的薄膜之上,避免非晶硅在硅片表面的外延生长。在退火过程中,高氢稀释比薄膜中的氢扩散到低氢稀释比薄膜中,有效地钝化了非晶硅中和单晶硅表面的悬挂键,改善了非晶硅/硅片的界面质量,叠层钝化后硅片的少子寿命为7.36 ms,隐含开路电压为732 mV。

Study on Passivation of Monocrystalline Silicon by Tandem Hydrogenated Amorphous Silicon Film

Studies on the passivation of monocrystalline silicon wafers by using plasma enhanced chemical vapor deposition for the deposition of monolayer intrinsic hydrogenated amorphous silicon films show that increasing the hydrogen dilution ratio is beneficial to reducing the defects in the films and enhancing the passivation effect.Excessive hydrogen dilution ratio can lead to the epitaxial growth of amorphous silicon on the silicon wafer surface and reduce the passivation effect.Annealing results in the increase of the degree of crystallization of amorphous silicon and the reduce of passivation effect.Meanwhile,annealing improves the quality of thin films and changes the way of H bonding and enhances the passivation effect.Therefore,the best passivation effect of monolayer hydrogenated amorphous silicon can be obtained only at appropriate hydrogen dilution ratio and annealing temperature.In order to improve the passivation effect of amorphous silicon film on silicon wafer,tandem intrinsic amorphous silicon film with high and low hydrogen dilution ratio is used to passivate silicon wafer.Therefore,the epitaxial growth of amorphous silicon on the silicon wafer surface can be avoided by stacking amorphous silicon thin films with high hydrogen dilution ratio on the thin films with low hydrogen dilution ratio.In the annealing process,the hydrogen in the film with high hydrogen dilution ratio diffuses into the film with low hydrogen dilution ratio,effectively passivating the suspension bonds on the surface of amorphous silicon and monocrystalline silicon,and improving the interface quality of amorphous silicon/silicon wafer.After the tandem passivation of the silicon wafer,the effective minority carrier lifetime is 7.36 ms,and the implied open-circuit voltage is 732 mV.