Present Status of the Surface Photovoltage Method (SPV) for Measuring Minority Carrier Diffusion Length and Related Parameters

The authors present an overview of the physics and practical issues related to surface photovoltage measurement of the minority carrier diffusion length and its application to monitoring recombination center defects in silicon. A tutorial description is given of the role of pertinent processes like injection, recombination and trapping. The evolution of the SPV method is presented followed by a description of most recent refinements addressing the measurement of long diffusion lengths in silicon wafers with emphasis on accuracy, measuring speed, tool-to-tool reproducibility and, practically the most important question of monitoring, iron concentration.