A scanned cw Ar ion laser was used to recrystallize polycrystalline and amorphous silicon films.N‐channel metal‐oxide‐semiconductor transistors were fabricated on these recrystallized films and used for electron field effect mobility measurements. The electron conduction in the samples which had polycrystalline silicon substrates and were annealed at higher power (⩾12 W) was dominated by the lattice scattering mechanism. Other relatively minor factors, such as the scattering by surface imperfections, impurities, and very small intercrystalline potential barriers, altered the magnitude and the temperature dependence of the measured mobilities. For the unannealed and lower power (⩽11 W) annealed polycrystalline samples, scattering at the intercrystalline potential barrier dominated the electron conduction. The role of additional phosphorus doping in the substrate is also discussed. In the higher power annealed polycrystalline devices, the scattering caused by the ionized phosphorus atoms not only lowered the magnitude but also reduced the negative temperature coefficient of the mobility. For the lower power annealed devices, the segregation of the phosphorus atoms to the grain boundary regions may be responsible for the lack of increase of the positive temperature coefficient in the mobility measurements. The unannealed and annealed (10–15 W) amorphous silicon samples also showed that the electron conduction was dominated by scattering at the intercrystalline potential barrier.