The process of Polymer Assisted Chemical Vapor Deposition (PACVD) and the semiconductor, dielectric, passivating or protecting thin films produced by the process are described. A semiconductor thin film of amorphous silicon carbide is obtained through vapor deposition following desublimation of pyrolysis products of polymeric precursors in inert or active atmosphere. PA-CVD allows one or multi-layers compositions, microstructures and thicknesses to be deposited on a wide variety of substrates. The deposited thin film from desublimation is an n-type semiconductor with a low donor concentration in the range of 10.sup.14-10.sup.17 cm.sup.-3. Many devices can be fabricated by the PA-CVD method of the invention such as; solar cells; light-emitting diodes; transistors; photothyristors, as well as integrated monolithic devices on a single chip. Using this novel technique, high deposition rates can be obtained from chemically synchronized Si--C bonds redistribution in organo-polysilanes in the temperature range of about 200-450.degree. C.