We investigated the properties of P-doped microcrystalline silicon (${mu}c$-Si) films prepared by PECVD at various substrate temperatures(150 to $400^{circ}C$) and $PH_3/SiH_4$ ratio ($7.55{ imes}{10^{-3}}$to $1.21{ imes}{10^{-2}}$). The volume fraction of ${mu}c$-Si in the films was a maximum of about 60% at $200^{circ}C$ and then decreased with further increase in substrate temperature. ${mu}c$-Si was formed when the $PH_3/SiH_4$ ratio exceeded a certain critical value, below which only amorphous silicon was deposited. The volume fraction of ${mu}$-cSi continuously increased with further increase in the $PH_3/SiH_4$ ratio. The electrical resistivity and the hydrogen content in the films sharply decreased when the ${mu}c$-Si was formed even though the volume fraction of the ${mu}c$-Si was much smaller than that of the amorphous. The optical band gap also decreased by the formation of the ${mu}c$-Si.