A novel analysis method to determine the surface recombination velocities on unequally passivated surfaces of a silicon wafer by the short wavelength spectrum excited quasi-steady-state photoconductance measurement

Abstract

In this work, we propose an analysis approach to determine the individual surface recombination velocities (S1 and S2) on each surface of an unequally passivated wafer, which precludes the crude assumption of S1=S2 in conventional methods. Taking advantage of the surface distributed excess charge carriers relatively sensitive to the surface recombination, we probe the sample using quasi-steady-state illumination of the xenon flash lamp equipped with a short pass filter (FSP1). A set of samples passivated by SiO2 and SiNx, as well as bare silicon wafers, are prepared in the experiment. On the basis of fitting the measured time-dependent-excess charge carriers, S1 and S2 are determined based on our analysis approach. The spatial and the temporal distributions of excess charge carrier density are presented. The dependence of τeff on the wavelength, S and τbulk is also discussed in detail. The reliability of this method is finally verified with a long pass filter (FLP2).