Doped hydrogenated amorphous‐microcrystalline mixed‐phase silicon (&mgr;c‐Si:H) films were prepared by the mercury photosensitized decomposition of a disilane‐hydrogen gas mixture, by adding phosphine and diborane fornandptype, respectively. The maximum dark conductivity and optical band gap of the films were, respectively, 20 S cm−1and ∼2.0 eV forntype, and 1 S cm−1and 2.3 eV forptype. It is most significant that the gaseous ratio of hydrogen to disilane should be enhanced up to 70 forntype, and even 300 forptype, to obtain such a highly conductive and wide gap film. The crystallinity of the photodeposited &mgr;c‐Si films appeared to be improved in comparison with that of films by conventional plasma glow discharge technique.