Carrier lifetime characterization using an optimized free carrier absorption technique

We investigated the correlation of the high-level lifetime of platinum-diffused power diodes with the platinum diffusion temperature, varying over a range of 40 K, and the operating temperature, varying from 223K to 398K. The high-level lifetime has been extracted from carrier profiles determined by an optimized free carrier absorption technique, assuming a homogeneous lifetime over the base region. We find an exponential dependence of the high-level lifetime on the operating temperature and no dependence of the injection levels under investigation. Therefore, the recombination processes can be properly described by using the Shockley-Read-Hall model in the electrothermal device simulation. The mean high-level-lifetime for a calibrated device simulation is only 20% lower than the experimentally determined one. The simulated carrier distributions are in very good agreement with the experiment if a weak lifetime gradient in the base region is assumed.