Back Cover: Recombination via point defects and their complexes in solar silicon (Phys. Status Solidi A 10/2012)

The back-cover image, taken from the Feature Article by A. R. Peaker et al. (pp. 1884–1893), depicts a map of the minority carrier lifetime of an inexpensive form of silicon used to manufacture solar photovoltaic cells. The silicon is cast from relatively impure feedstock and is much cheaper than electronic grade silicon grown by conventional Czochralski or float zone methods. However, the minority carrier lifetime and hence the efficiency of solar cells made from it are considerably less than electronic grade. The picture shows the variation of lifetime between grains represented by a spectrum of colours (red relates to a short lifetime while blue indicates the longest lifetime). It can be seen that variations occur across the material not necessarily related to the grain boundaries. Maps such as this, used in conjunction with other techniques, can enable the lifetime to be correlated with specific defects and recombination processes and, in favourable circumstances, enable much higher efficiencies to be achieved.