Light‐induced changes in the photo‐, &sgr;ph, and dark, &sgr;d, conductivities of undoped hydrogenated amorphous silicon (a‐Si:H) and amorphous silicon–carbon are investigated as functions of deposition and measurement temperature. Previous work described the temperature dependence of the annealed state &sgr;phand &sgr;dof a series of intrinsica‐Si:H materials deposited over a range of substrate temperatures, 200 °C<Ts<380 °C, and a thermal equilibrium framework for the high temperature behavior of the relationship between concentrations of dangling bond defects (DBs) and free carriers. The annealed‐state results are extended to the light‐degraded state where elevated temperatures ensure equilibration of the free carrier and DB concentrations as suggested by the thermal equilibrium framework. Both &sgr;dand &sgr;phin the light‐degraded‐equilibrium state decrease compared to the annealed state while the ratio, &sgr;d/&sgr;ph, remains unchanged. From this result, relationships between the Fermi level and the ratio of positively and negatively charged DBs are derived in terms of the thermal equilibrium framework equations. ©1996 American Institute of Physics.