Influence of Nickel Silicide Thin Film on Series Resistance of Silicon Solar Cells

In this paper, the influence of nickel silicide thin film on series resistance of silicon solar cells is investigated. The frontside two-layer electrodes are fabricated by the light induced electroless plating of nickel and light-induced plating of silver. The nickel films are deposited onto the silicon wafers surface by light induced electroless plating in the nickel-plating bath containing main nickel source. The nickel film thicknesses of 200 nm, 400 nm and 600 nm are identified by the SEM observations. The formation of nickel silicide thin films are obtained after the thermal annealing process for 1 min, 3 min and 5 min. The nickel silicide thin film reduces the series resistance mainly due to the decrease of contact resistance between metal electrode and silicon substrate. The reduction in contact resistance and series resistance are confirmed by using transmission line model analysis and dark current-voltage characteristics in experiment. The improvement of series resistance extracted from the dark current-voltage curve in the upper voltage range is observed. The minimum series resistances of silicon solar cells with different nickel film thicknesses are obtained after different thermal annealing periods, respectively. The silicon solar cell with nickel film of 400 nm thick after thermal annealing process of 3 min possesses the minimum series resistance of 0.66 Ω cm2.