This work investigates the interface properties of intrinsic hydrogenated amorphous silicon film passivated wafers that underwent hydrogen plasma cleaning. A high level of interface band bending of nearly À0.6 eV, which corresponds to a fixed charge of À2.2 Â 10 12 cm À2 , is found to be responsible for an effective minority carrier lifetime of over 6 ms on the 4.5 Ω cm n-type wafer, while such field-effect passivation is missing in hydrofluoric acid (HF) cleaned wafers. Further study indicates a positive correlation between the extent of surface band bending and doping concentration, together with an inverted U-shape with respect to the increased annealing condition. The fixed charge on p-type wafer is found to have a higher "formation energy" compared with the n-type case, which renders its field-effect passivation much less effective due to H effusion at high annealing temperatures. With reference to the theory on donor/acceptor-H complex upon H plasma treatment, the origin and observed properties of the surface band bending on both dopant types are discussed. The unique presence of field effect on hydrogen plasma cleaned n-type wafers can provide new insights into passivation material selection and structural design of heterojunction silicon wafer solar cells.

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