Abstract
Mesa structures of different diameters (0.2–1.2 mm) are used to determine bulk minority-carrier lifetime based on current transients in multicrystalline silicon (Mx-Si) solar cells. Single-shot nanosecond rise time pulse testing is used for Mx-Si diodes to reveal unique information not obtained by conventional direct- current electrical testing. In this paper, effective lifetime is extracted from the recovery switching transient that is dominated by surface recombination effects. The perimeter/area ratio from different sizes of mesas removes the effect of perimeter recombination. The minority-carrier lifetime is determined as 85 µs (high efficiency, 13.37%) for sample A and 21 µs for sample B (low efficiency, 5.22%) made from the same Mx-Si ingot. The similar method gives 105 µs for Czochralski silicon (Cz-Si). The surface recombination velocities were 2800 cm/s for sample A, 5800 cm/s for sample B of Mx-Si, and 4700 cm/s for Cz-Si. This confirms that the recovery-switching transient is a suitable method for determining the minority-carrier lifetime in Mx-Si solar cells.