One of the principal difficulties in applying the Zerbst analysis to MOS capacitor transient recovery is the extremely long retention time of the MOS capacitor in high lifetimematerials. Typically the retention time is thousands of seconds at room temperature, so long times are required for a significant number of measurements. Furthermore, extrapolating the result of high temperature measurements back to room temperature can lead to large errors. A modified C—t transient response using a step from accumulation to depletion followed by light and then a small step from inversion to stronger inversion speeds up the generation lifetime measurement and separates the surface generation from the bulk generation. Pre— and post—epitaxial intrinsically gettered p/p+ wafers were subjected to high temperature CMOS process simulation and MOScapacitors with Al dots and guard rings were fabricated. Generation lifetime of about 5 msec were measured using the modified fast Zerbst method on properly intrinsically gettered epitaxial wafers, particularly the pre—epitaxial intrinsically gettered wafers.