uv Microprobe Technique for Measurement of Minority-Carrier Diffusion Length in GaP p-n Junction Material

Abstract

The minority‐carrier diffusion length on either side of a GaP p‐n junction have been determined from measurements of the short‐circuit current under uv excitation. The uv lines at 3.41 and 3.53 eV are extracted from an Ar laser and are focused to a spot 10 μ in diameter. The uv spot is scanned along the angle‐lapped surface of the junction to obtain the variation of short‐circuit current as a function of distance normal to the junction from which the diffusion length is derived. The technique provides a determination of diffusion lengths as short as 0.13 μ with an accuracy of 15%. The technique is straightforward and should be useful in the evaluation of GaP and other semiconductor material containing p‐n junctions.