3D‐resolved determination of minority‐carrier lifetime in planar silicon solar cells by photocurrent decay

In modern production schemes for Si solar cells, defect passivation and impurity gettering are often used to improve material quality and thereby cell efficiency. These processes generally alter the spatial uniformity of minority‐carrier transport parameters over the wafer and may result in minority‐carrier lifetime and diffusion length variations both lateral and in depth. In polycrystalline Si these spatial dependences are already present due to the nature of the material. We present an extension of the photocurrent decay method to determine the diffusion length in a three‐dimensionally resolved fashion. From a single photocurrent decay curve the back‐surface recombination velocity, the average minority‐carrier diffusion length, and an asymmetry factor which qualitatively describes the depth dependence of the diffusion length are determined. This is done using the three observables: quantum efficiency, fundamental decay time, and intercept of the extrapolated decay curve with the time‐zero axis. Lateral...

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