Photochemical conversion of electrically conductive polysilane films into insulators

Electrically conductive polysilane films doped with iodine can be converted into insulators to semiconductors by a photooxidation reaction. The conductivity can be controlled in the range 10−15–10−4 S cm−1 by regulation of the extent of the photooxidation reaction. Since the non-irradiated area of the film keeps its doping susceptibility, it is possible to prepare a conducting pattern on the film by a photolithographic technique. Network polysilanes containing various substituents, prepared by the disproportionation reaction of alkoxydisilanes, were primarily examined, in addition to polysilanes prepared by the Wurtz coupling reaction. UV and IR analyses indicated that the Si-Si bonds in the polysilanes were changed into Si-O-Si bonds and Si-OH bonds by the photooxidation.