Physical criteria for the interface passivation layer in hydrogenated amorphous/crystalline silicon heterojunction solar cell

AFORS-HET (automat for simulation of heterostructures) simulation was utilized lo explore the physical criteria for the passivation layer in hydrogenated amorphous/crystalline silicon heterojunction (SILT) solar cells, by systematically investigating the solar cell current density-voltage (J-V) performance as a function of the interface defect density (D-it) at the passivation layer/c-Si hetero-interface, the thickness (t) of the passivation layer, the bandgap (E-g) of the passivation layer, and the density of dangling bond states (D-db)/band tail states (D-bt) in the band gap of the passivation layer. The corresponding impact regulations were presented clearly. Except for D-it, the impacts of Ddb, D-bt and E-g are strongly dependent on the passivation layer thickness t. While t is smaller than 4-5 nm, the solar cell performance is less sensitive to the variation of D-db, D(bt)and E-g. Low D-it at the a-Si:H/c-Si interface and small thickness t are the critical criteria for the passivation layer in such a case. However, if t has to be relatively larger, the microstructure, i.e. the material quality, including D-db, D-bt and E-g, of the passivation layer should be controlled carefully. The mechanisms involved were analyzed and some applicable methods to prepare the passivation layer were proposed.