Laser Scanning Technique for the Detection of Resistivity and Lifetime Inhomogeneities in Semiconductor Devices

Using a light spot scanner it is possible to get a point by point measurement of carrier lifetime and resistivity inhomogeneities in a semiconductor crystal. Up to now a drawback with this method has been the uncontrollable influence of the surface. We will present a simple technique (a quotient method) where all major surface effects are eliminated. Using this technique we can easily image inhomogeneities and also separate fluctuations due to local variation in carrier lifetime from those due to variation in resistivity.