High-resolution lifetime mapping using modulated free-carrier absorption

Abstract
Modulated free-carrier absorption (MFCA) is introduced as a novel contactless lifetime mapping technique with high spatial resolution. The advantages of MFCA mapping as compared to other methods are discussed. Examples of lifetime maps on multicrystalline silicon are presented. Solar cells fabricated from identical wafers have been investigated using light beam induced current mapping. Excellent agreement between structures obtained in the measured lifetime and in the current maps was observed. In addition, a quantitative comparison with diffusion lengths determined by local internal quantum efficiency evaluations is presented.