Diffusion Lengths of Electrons and Holes in GaAs

Abstract

The short‐circuit current of both diffused and n‐type metal semiconductor junctions during 2‐MeV electron irradiation was measured. The results indicate that electron diffusion length in the Zn‐diffused p‐type region is proportional to the reciprocal of the square root of the donor concentration. The electron‐diffusion length ranges from 20 μ for lightly doped diodes to 2 μ for heavily doped diodes. The hole‐diffusion lengths are less than 1.0 μ in heavily doped surface barrier diodes. The thickness of the active radiative recombination region for diffused diodes under forward bias was measured and compared with the short‐circuit current results. These results suggest that the pre‐irradiation electron lifetime is ≈ (10⁻⁹ N_D)⁻¹, where N_D is the substrate donor concentration. This behavior is consistent with radiative recombination between donors and free holes.