Gate-length dependence of bulk generation lifetime and surface generation velocity measurement in high-resistivity silicon using gated diodes

The accuracy of the gated-diode method for extracting bulk generation lifetime and surface generation velocity in high resistivity silicon is shown to depend critically on the gate length of the adopted test device, as a result of nonidealities which are not accounted for by the measurement technique. Minimization of the surface generation velocity measurement error requires the gate length to be suitably reduced, while long gate devices are needed for accurate bulk generation lifetime extraction. Both parameters can be measured from a single test structure obtained by compenetrating a short gate device with a long gate one.