Measurement of the minority-carrier lifetime using an MOS capacitor

A simple technique is described for the measurement of the minority-carrier recombination lifetime using an MOS capacitor operating as a charge injection device. Device lag resulting from the incompleteness of the charge injection process is measured as a function of the injection pulse width. An approximate diffusion model consisting of only one adjustable parameter, the recombination lifetime, is able to explain the observed lag data. The values of the recombination lifetime thus obtained are in good agreement with those measured by photoconductive decay for a variety of Si samples. This technique permits a more definitive measurement of the minority-carder lifetime in fabricated devices than presently used procedures, without requiring high-quality devices. This technique should be particularly useful for evaluating III-V and II-VI compound semiconductors because MOS capacitors with a low density of interface states often are not available.