Annealing effect on surface passivation of a-Si:H/c-Si interface in terms of crystalline volume fraction

We present post-deposition annealing results of intrinsic amorphous/n-type crystalline silicon heterostructure in terms of quantified crystalline volume fraction in the amorphous silicon thin film, calculated from spectroscopic ellipsometry measurement. Regardless of layer thickness and deposition parameters, heterostructures with under-10% crystallinity show greatly improved effective lifetime, while more-than 10%-crystalline heterostructures are detrimented by thermal annealing. Even under the same deposition condition, effective lifetime of annealed heterostructures differ to a great extent in terms of layer thickness, since the initial grown epitaxy is critical in surface passivation with device-level thickness. 0%-crystalline heterostructure with improved passivation via annealing was demonstrated. We suggest the rearrangement of mobile hydrogen atom and uptake of mobile hydrogen at the interface between crystalline phase and amorphous layer as the mechanism of this annealing behavior, based on subsequent analysis including FT-IR and HR-TEM.