Carrier de-smearing of photoluminescence images on silicon wafers using the continuity equation

Abstract

Photoluminescence images of silicon wafers with non-uniform lifetime distribution are often smeared by lateral carrier diffusion. We propose a simple method to de-smear the photoluminescence images by applying the two-dimensional continuity equation. We demonstrate the method on simulated silicon wafers and measured photoluminescence-based lifetime image of multicrystalline silicon wafer. The de-smearing is very effective in recovering the actual lifetime for wafers with gradual changes in lifetime but is less effective around localised recombination centres with high contrast such as grain boundaries and dislocations. The method is sensitive to measurement noise; therefore, the implementation of suitable noise filtering is often critical.