Neutral higher silane molecules in silane radio frequency glow discharge plasmas are investigated using photoionization mass spectroscopy at various radio frequency (rf) powers and total pressures. Densities of higher silane molecules increase with rf power up to 10 W, and then decrease at 10–100 W. The reduction of the neutral higher silane molecules at high rf power suggests that these molecules contribute to the particle formation through secondary reactions in the plasma. ©1998 American Institute of Physics.