The Principle of Adaptive Excitation for Photoluminescence Imaging of Silicon: Theory

An approach that determines the charge carrier lifetime from photoluminescence (PL) imaging that is virtually not affected by lateral charge carrier drift and diffusion and image smearing due to photon scattering is proposed. The approach attempts to create a laterally uniform charge carrier density within a sample with non-homogeneous recombination properties via illumination with spatially varying intensity. Lateral excess charge carrier drift and diffusion is inherently absent in this situation. Furthermore, as a homogeneous PL intensity is monitored, any optical artefact induced by photon scattering in the investigated wafer or the detection charge-coupled device is strongly suppressed compared to conventional PL imaging. Using numeric simulations of different lifetime distribution scenarios, including one based on measured micro-photoluminescence (-PL) lifetime data, we demonstrate the feasibility of this proposed Adaptive Excitation Photoluminescence Imaging (Ax-PLI) method.