Structural characterization of the material has been performed using micro-Raman spectroscopy, ultraviolet (UV) ellipsometry, electron microscopy and micro-photoluminescence (PL) studies on Si:H films prepared at a wide range of Ar dilution to the SiH4 plasma, defined by R(Ar)=Ar/SiH4 and varying from 10 to 400. Microcrystallization in Si:H network was easily obtained introducing Ar as a diluent, however, increasing Ar dilution revealed a continuous transformation of the network from microcrystalline to amorphous dominated structure. An overall amorphization of the network and its initiation by the presence of an enormously high void density (similar to 81 vol.%) in an extended incubation layer (similar to 163 nm) is the result of extremely high Ar dilution (R(Ar)similar to 400), on the formation of Si:H films. Increasing porosity in the amorphous dominated matrix resulted in a significant increase in the photoluminescence intensity, contributing to a photoluminescent Si:H material available from extremely high Ar dilution to the SiH4 plasma in rf glow discharge. Effect of Ar dilution inducing the growth morphology by controlling both the gas phase reactions and solid phase network modifications in Si:H network has been discussed. (c) 2004 Elsevier B.V. All rights reserved.