By measuring both the mechanical stress and the optoelectronic properties of a-Si:H films before and after light-soaking, we have examined the film structural stability in relation to its electronic stability. A photoinduced increase of the compression, in the order of10−4of the initial value, was found in both the glow discharge and hot-wire films. A factor of 4-6 photodegradation of the photoconductivity was obtained in the HW films deposited atTS<360&hthinsp;°C,but there was no photodegradation for the films deposited at360<TS<440&hthinsp;°C.Hence, there is no obvious relation between the changes in film structure (observed by IR and stress) and the Staebler—Wronski Effect (SWE). ©1999 American Institute of Physics.