Advances in infrared imaging methods for silicon material characterization

Infrared imaging methods have been demonstrated as being valuable means to extract information about material quality. The main parameters under investigation are the minority carrier lifetime, the free carrier density (base doping, emitter diffusion), and the trap density. Infrared imaging methods are mainly based on the detection of infrared radiation emitted by the sample. Depending on the origin of the radiation, recombination luminescence in the near infrared or free carrier emission in the mid wavelength infrared is recorded. We present the state of the art of infrared imaging techniques for silicon material. These include Carrier Density Imaging / Infrared Lifetime Mapping, Photoluminescence Imaging for fast lifetime measurements, and trap density measurements for advanced defect characterization. Emphasis is put on the correction of spurious surface effects, on calibration techniques for Photoluminescence Imaging, on progress in trap characterization, and on diffusion length measurements on solar cells.