The effect of light soaking on the steady‐state reverse bias collection efficiency has been studied for hydrogenated amorphous silicon films produced by reactive magnetron sputtering. Films with optical gaps of 1.63 and 1.74 eV both showed considerable degradation in the collection efficiency, correlating with increases in sub‐gap absorption and decreases in the spectral response quantum efficiency. The collection efficiency data have been fitted with the two‐field Hecht expression, and effective mobility‐life‐time products have been extracted. These results indicate that straightforward measurements on Schottky barriers can be utilized as sensitive monitors of light induced degradation in a‐Si:H