Microscopic electrical characterization of fixed-charge-controlled passivation films for Si solar cells

A scanning capacitance microscopy (SCM) has been applied to the electrical characterization of passivation films for crystalline Si solar cells. An Y₂O₃-Al₂O₃ system, which is a binary composition spread oxide film, was used as a fixed-charge-controlled passivation film. The flat-band voltages of the Y₂O₃-Al₂O₃ system were determined from microscopic C-V curves measured by the SCM. The result was in agreement with that of a conventional C-V method. Additionally, the dV/dC images measured by the SCM were investigated for visualizing the spatial distribution of interface trap density.