Determination of Diffusion Lengths With the Use of EBIC From a Diffused Junction With Any Values of Junction Depths

Minority carrier diffusion lengths determine the performance of bipolar and photodiode devices. An electron-beam- induced-current (EBIC) method has been widely used to extract this parameter. The extraction of the diffusion lengths involves a p-n junction to collect the minority carriers. The most used configuration, which is called the normal collector, assumes that the junction has an infinitely large junction depth. However, in planar devices, the junction depth is comparable to the diffusion lengths of the material. This paper presents a simple and yet accurate method to determine the diffusion lengths of the material from a diffused junction with any values of junction depths. The diffusion length of the material is extracted from the negative reciprocal of the slope of the EBIC profile in semi-logarithmic plot. It was found that the proposed method is able to extract the diffusion lengths accurately for any values of the junction depths and surface recombination velocities. The maximum error in using this method is about 6%