Measurement techniques for high-resistivity detector-grade silicon

Techniques for nondestructively characterizing the resistivity and excess-carrier recombination lifetime in ingots of high-resistivity, long-lifetime detector-grade silicon are evaluated. In particular, three interrelated techniques for nondestructively: measuring an average resistivity, profiling the low-level excess-carrier lifetime, and profiling the resistivity of cylindrical specimens are proposed and are in the process of being evaluated. All three techniques treat the ingot under test as a large van der Pauw specimen and require removable silver-paste contacts or pressed-on capacitive contacts. The profiling measurements use a highly penetrating 1.15 micrometer He-Ne laser beam as an optical probe. The conceptual and theoretical background for these measurements and the results of feasibility experiments are presented.