Electrical and Optical Defect Evaluation Techniques for Electronic and Solar Grade Silicon

We review techniques which characterize and quantify the properties of defects and impurities in silicon materials and devices in terms of their effect on free carriers and their recombination- generation behavior. In particular we explore the application of Deep Level Transient Spectroscopy (DLTS) and its many variants to electronic and solar grade silicon. The physics of carrier recombination at deep level defects is presented and the various methodologies to measure defect parameters related to Shockley-Read-Hall generation-recombination kinetics are discussed. The use of high resolution Laplace DLTS is presented and techniques for determining characteristics of minority carrier traps are explained. Methods to measure minority carrier lifetime and relate these measurements to the defect concentrations and properties are considered. Optical measurements to study defects are presented including optical absorption, Raman techniques and photo-luminescence. The status and limitations of such techniques for qualification of silicon material are discussed.