The quantum efficiency (QE) of light-induced metastable defect creation in hydrogenated amorphous silicon (a-Si : H) and amorphous As2Se3 (a-As2Se3) by bandgap and subgap illumination has been deduced from photocurrent measurements. The QE decreases with increasing number of absorbed photons. A higher QE for a-As2Se3 than for a-Si : H has been observed and this is interpreted in terms of the higher structural flexibility of a-As2Se3. We have also found that, for both materials, subgap illumination yields a higher QE than (...) does bandgap illumination. (shrink)