The correlations between structural, chemical, electrical, optical properties of in situ phosphorus-doped hydrogenated microcrystalline silicon prepared by plasma-enhanced chemical vapor deposition have been studied by high-resolution transmission electron microscopy, secondary-ion mass spectrometry, electrical conductivity, and optical measurements. Microcrystallinity has been observed at a substrate temperature as low as 100-degrees-C with a 1% dilution of (1% PH3/SiH4) in H-2. In situ phosphorous-doped hydrogenated microcrystalline silicon is best grown at 200-300-degrees-C in terms of microstructure, H and P content, and dopant activation. The effects of thermal processing and the use of silicon nitride cap deposited prior to anneal on the structure and properties of phosphorous-doped hydrogenated microcrystalline silicon are also reported. The use of a silicon nitride capping layer is shown to inhibit recrystallization of hydrogenated microcrystalline silicon during rapid thermal anneal.