Generalized EBIC method for extracting diffusion lengths from non-conventional collector structure

The minority carrier diffusion lengths affect the performance of the bipolar and photodiode devices. The electron beam induced current (EBIC) technique has been widely used to determine this parameter. The measurement usually involves a p-n junction which assumes very large junction depths. However, most p-n junctions are fabricated as diffused junction with finite junction depths. This article proposes a generalized method to determine the diffusion length for any values of junction depths and surface recombination velocities. The diffusion length of the material is extracted directly from the negative reciprocal of the slope of the semi-logarithmic EBIC profile. The maximum error produced by this method for any values of junction depths and surface recombination velocities is about 6%. A discussion of this technique is given in this paper.