Ion bombardment-induced defect reduction at a-Si:H/c-Si interfaces: possible microstructural changes and mobile hydrogen roles

Abstract A beneficial effect of argon (Ar) ion bombardment for crystalline silicon (c-Si) surface passivation has been studied. Experiments of an Ar plasma treatment over an hydrogenated amorphous silicon (a-Si:H) layer grown on c-Si are performed, where an a-Si:H layer is prepared at different levels of defect density. Interestingly, the c-Si surface passivation is improved by an Ar plasma treatment for a defect-rich, i.e. low-quality, a-Si:H layer, while it is deteriorated by the treatment for a low-defect, i.e. high-quality, a-Si:H layer. The improvement of passivation is discussed in terms of microstructural changes of a-Si:H, associated with redistribution of hydrogen, where mobile hydrogens play an important role.