Amorphous silicon-carbon-fluorine alloy films

A new amorphous semiconductor alloy system SiₓCₓFy has been prepared by rf sputtering of polycrystalline SiC in an Ar+SiF₄ atmosphere. Dark conductivity and optical absorption of thin films are measured as functions of F concentration. Infrared spectra indicate a preferential attachment of fluorine to carbon over silicon. The bonded fluorine concentration is estimated to be as high as 40 at.%. The principal reststrahlen band shifts to higher frequencies and appears to sharpen with the increase of fluorine concentration. Fluorinated films are observed to be resistant to high-temperature annealing.