Abstract
A new technique is presented for determining the transport properties of minority carriers (the diffusion length and recombination velocity) generated when polycrystalline grains, with a grain size smaller than the diffusion length, are irradiated by an electron beam. An analogous case that can be handled using this technique is the determination of the recombination velocity at the interface between an epitaxial layer and a heavily doped substrate with a very short lifetime. For 1–2‐μm grains in a polycrystalline GaAs solar cell, we found that the diffusion lengths can equal bulk‐diffusion lengths observed in single‐crystal material, but high recombination levels prevail at the grain boundaries, the recombination velocity there may reach 2×106 cm s1 and is inversely proportional to the grain size.