Particle growth processes and the contribution of shea lifetime radicals to the processes in SiH4 high frequency plasmas for a moderately high power above 0.25 W/cm(2) are studied using polarization-sensitive laser light scattering, a newly developed Langmuir probe, a novel photodetachment, transmission electron microscopy, atomic force microscopy, and intracavity laser absorption methods together with a discharge modulation method. Particles are generated and grow from their nucleation phase principally around the plasma/sheath boundary near the powered electrode. Spatial profiles of the particle amount are very similar to those of production rates and densities of short lifetime radicals. The SiH2 density is low in spite of its high production rate. While the SiH2 density in the early discharge stage for 28 MHz is about one order higher than that for 6.5 MHz, the particle density for 28 MHz is two orders higher than that for 6.5 MHz. These results suggest that short lifetime radicals, in particular SiH2 radicals, not only participate mainly in the particle nucleation but also contribute numerous times to the nucleation and subsequent initial growth reactions of one particle. Moreover, photodetachment measurements showed that clusterlike particles exist even in the bulk plasma; some of them are considered to be neutral and hence they are likely to be transported to the substrate on the grounded electrode.