Mapping the quantitative carrier lifetime and doping concentration with micro resolution

The measuring technique depicted in this work provides a quantitative carrier lifetime and doping concentration mapping with a spatial resolution of down to 1 µm. While the typical resolution limit of established mapping and imaging methods is limited due to large diffusion lengths above 5 µm, our setup significantly enhances this limit by measuring under high injection levels. This allows for detailed quantitative analyses on the recombination activity of defects such as grain boundaries and dislocations, and on the doping concentration of microscopic technological structures. The presented technique is based on confocal micro photoluminescence spectroscopy. The confocal microscope setup permits for focussed laser illumination and fast low-noise detection of the emitted luminescent radiation. The carrier lifetime and doping concentration is determined by a calibration of the depth dependent luminescent radiation with results from two-dimensional simulations generated by the continuity equations