Spatially resolved investigations of lifetime enhancement in vertically grown, multicrystalline silicon ribbons

This aspect of spatial resolution has been found to be indispensable for investigating the impact of different processing steps on material quality in an accurate way. Apart from strong variations in as-grown lifetimes that have been found throughout vertically grown silicon wafers, this is due to areas of comparable starting lifetimes which have been revealed to react very differently to applied processing steps. After processing, some of them reach minority charge carrier lifetimes of more than 300 μs whereas others just show values of a few microseconds. As a consequence, the results of integral measurements strongly depend on the nature of areas incorporated in the specific sample. An impression of the corresponding uncertainties inherent to integral measurements has been obtained by statistical evaluation of spatially resolved lifetime data.