Using infrared (IR) absorption measurements, it is proposed that amorphous hydrogenated silicon films obtained from plasma‐enhanced chemical vapor deposition of Silane (SiH4) highly diluted in helium at high rf‐power densities, consist of an amorphous tissue in which a columnar microstructure is embedded. The evolution of the IR spectrum with dilution evidences a remarkable tendency to the substitution of monohydrides by dihydrides. The films show high transparency and good conductivity. These properties make them suitable to be used as window layers for thin‐film solar cells when conveniently doped.