Photocurrent and diffusion lengths at the vicinity of grain boundaries (g.b.) in N and P-type polysilicon. Evaluation of the g.b. recombination velocity)

Photocurrents, diffusion lengths (L) and g.b. recombination velocities (s) have been measured by optical scanning in N and P-type polysilicon. With type of grains, L is found to vary between 5 μm and 150 μm and s is always higher than 104 cm.s-1. The results on local measurements of diffusion lengths show that the vicinity of a g.b. is highly stressed. It seems that the g.b. potential barriers are higher in N-type than in P-type.