p‐Type microcrystalline Si films have been prepared by rf decomposition of SiH4/H2/BF3gases. The gas composition, substrate temperature, and rf power dependence of film conductivity &sgr; are investigated. The &sgr; increases with increasing BF3and saturates or takes a maximum at [BF3]/[SiH4]∼1. A fairly high &sgr; value of ∼1.2×10−2S/cm is obtained for the low rf power (∼0.1 W/cm2). Increasing rf power decreases &sgr;, which is in contrast to the SiH4/H2/B2H6system. The incorporation rate of boron from gas phase into the film is found to be low (∼4%) by use of secondary ion mass spectroscopy. Increasing hydrogen increases &sgr;. Temperature is found to be the most effective deposition parameter. The &sgr; monotonically increases with an increase of substrate temperatureTS. Transmission electron microscopy observation shows that films with higher &sgr; contain higher density or larger size Si crystallites. The crystalline size increases by a short time (≤15 min) annealing at 400 °C. The deposition parameter dependence of &sgr; in comparison to the SiH4/H2/B2H6system is discussed. The low temperature annealing effect is discussed in terms of film structure.