We measure light-induced D tracer diffusion in hydrogenated amorphous silicon samples under conditions at which thermal diffusion is negligible. Under high-intensity (9 W ${\mathrm{cm}}^{\mathrm{-}2}$), red-light soaking at 135 °C, the D diffusion coefficient is $D_{\mathrm{D}}=1.3\mathrm{}\times {10}^{-18}{\mathrm{cm}}^2{\mathrm{}\mathrm{s}}^{\mathrm{-}1}$ and the rate of D emission from Si-D to transport is $3.5\times {10}^{-5}{\mathrm{s}}^{\mathrm{-}1}.$ We also find an upper bound of $D_{\mathrm{D}}=3\mathrm{}\times {10}^{-20}{\mathrm{cm}}^2{\mathrm{}\mathrm{s}}^{\mathrm{-}1},$ the light-induced diffusion coefficient at 65 °C. Previous experiments had revealed only “light-enhanced” diffusion between from 200 to 300 °C, a regime in which thermal diffusion is also significant. Our 135 °C result extends the range of the 0.9-eV activation energy for this diffusion; our 65 °C upper bound is consistent with the extrapolation of the higher temperature data. We also measure metastable defect creation at 65 and 135 °C to test models of light-induced metastability that involve emission of H from Si-H bonds to an H transport level. This class of models can be limited, but not excluded, by our data. The H emission parameter of the H collision model of metastability is also estimated.

• Received 8 January 1998

DOI:https://doi.org/10.1103/PhysRevB.59.5513