Amorphous silicon–carbon based thin films deposited in a microwave plasma reactor using organosilane vapors from liquid sources show efficient photoluminescence (several %) when excited with ultraviolet (UV) light together with a low absorptivity (down to 1 cm−1at the long‐wavelength side) in the spectral range of the luminescence emission (400–550 nm). On the basis of these films we have prepared luminescent waveguiding layer structures which we propose for an application as a fast, sensitive, and selective UV detector integrated on silicon. ©1995 American Institute of Physics.