Capacitance spectroscopy of amorphous/crystalline silicon heterojunction solar cells at forward bias and under illumination

An original method of characterization of interface properties of hydrogenated amorphous silicon/crystalline silicon heterojunction solar cells is proposed. This is based on the measurement of the capacitance under AM1.5 illumination at forward bias close to the open-circuit voltage. The capacitance is very sensitive to the quality of both the front heterojunction and the back contact. The authors show that the comparison of the low-frequency capacitance with the open-circuit voltage can be used to deduce both the back surface recombination velocity of minority carriers and the front interface defect density. The technique can be applied to other types of solar cells. (c) 2007 American Institute of Physics.