Dynamic Infrared Lifetime Mapping for the Measurement of the Saturation Current Density of Highly Doped Regions in Silicon

Previously, the dynamic infrared lifetime mapping (ILM) approach was used for a spatially resolved determination of the reverse saturation current density J₀ of local highly doped regions in silicon. However, possible restrictions of the method have not been considered yet. We show that 1) injection dependent lifetimes, 2) a nonlinearity between camera signal and excess charge-carrier density, as well as 3) an additional signal due to a modulated sample temperature may affect the lifetime measurement and thus the correct determination of J₀. Moreover, we consider the impact of injection dependent lifetimes and the modulated sample temperature under high-level injection. We apply our approach to symmetrically phosphorous diffused and textured samples with sheet resistances between 23 and 150 Ω/sq. Using the adopted evaluation algorithm of the dynamic ILM technique, we obtain an agreement in J₀ evaluated by dynamic ILM and photo-conductance decay measurements of 8%.