Diffusion length and surface recombination velocity measurements with the scanning electron microscope: The highly-doped emitter of a p-n junction

Abstract

Analytical solutions of the electron-beam induced current response for a spherical source excitation are formulated for a finite region of semiconductor using the method of images. The analytic approach is different from that normally reported for semi-infinite region analysis because it incorporates a third boundary condition into the problem. Consequently, it is more general because it is valid for all regions of width greater than or equal to two real excitation volume radii. The analytic solutions predict that absolute, not relative, current responses must be used to determine diffusion lengths in finite regions of semiconductors and that the slope of the response is relatively insensitive to the surface recombination velocities. The solutions are demonstrated to correctly fit normalized data for the response of a highly-doped emitter.