Thin p/p+ epitaxial layer characterization with the pulsed MOS capacitor

The defect properties of thin p/p(+) wafer are not as easily characterized as those of bulk wafers. Recombination lifetime and minority carrier diffusion length measurements do not work well for thin layers, but generation lifetime characterization is eminently suitable. However, for thin epitaxial layers it is difficult to determine the correct generation lifetime because the linear portion of the Zerbst plot is too small to extract the generation lifetime when the applied gate voltage confines the space-charge region (scr) to the lightly doped epitaxial layer. For low gate voltages, moreover, the Zerbst slope is higher then that at high gate voltages. A sufficiently high gate voltage extends the scr to the out-diffused p(+) region. However, if the scr reaches the p' region, there is a drop off in the Zerbst plot. We have developed a mathematical analysis for this region. We have also extended the analysis to the measurement of possible p/p(+) interface imperfections, e.g. misfit dislocations. (C) 1998 Elsevier Science Ltd. All rights reserved.