Estimates of Diffusion Length in Amorphous Silicon

Amorphous silicon is not a conventional semiconductor in the sense already discussed. Undoped a-Si H as used in the base layer of an a-Si solar 

The diffusion length itself was first estimated from the properties of solar cells (Wronski, 1977 Konagai et al, 1980), usually from the dependence of short circuit current on reverse voltage at different wavelengths of excitation. Wronski estimated Lp = 0.2 fira, whereas the Japanese authors found their results consistent with a Lp of not greater than 0.05 fim. 

A direct method that depends on diffusion alone employed the photoelec-tromagnetic (PEM) effect (Moore, 1980). In this method a diffusive ffow of pairs is acted on by a magnetic field perpendicular to the flow. A current mutually perpendicular to both flow and field results. Analysis of the data yielded Lp = 0.09 /im. 

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