Thin films of amorphous silicon-oxygen-hydrogen alloys have been prepa
red by sputtering of silicon in water vapour. The obtained samples wer
e characterized by infrared absorption, Rutherford backscattering, ela
stic recoil detection, optical transmission, and luminescence measurem
ents. The appearance of a strong, visible (red) luminescence at room t
emperature for oxygen contents around 40 - 50 at% is discussed on the
basis of microscopic evidence deduced from optically detected magnetic
resonance.