Role of defects in the electronic properties of amorphous/crystalline Si interface

The mechanism determining the band alignment of amorphous/crystalline Si heterostructures is addressed with direct atomistic simulations of the interface performed using a hierarchical combination of various computational schemes ranging from classical model-potential molecular dynamics to ab initio methods. We found that in coordination defect-free samples the band alignment is almost vanishing and independent of interface details. In defect-rich samples, instead, the band alignment is sizably different with respect to the defect-free case, but, remarkably, almost independent of the concentration of defects. We rationalize these findings within the theory of semiconductor interfaces.