Photovoltaic applications have been developed mostly on silicon technology in order to generate electricity from solar energy by efficient conversion of solar spectrum. In this work, we have focused on the novel processing routes of Si nanocrystals (Si-NCs) in a remote expanding thermal plasma (ETP). Si-NCs were formed inside a SiH₄-Ar plasma by excessive heating of SiH_x clusters via electron and ion collisions. Formation routes of nanoparticles were investigated under different conditions by changing SiH₄ and Ar flow rates, deposition pressures and arc currents. The morphologies of the deposits were powder-like, consisting of densely packed crystalline particles and inter-space of amorphous Si. Due to the variations in plasma regions from center to side walls, the powder color and properties were different on the different parts of the deposited samples. The formation of nanoparticles on these parts was investigated by a number of diagnostic techniques. As a first exploration, transmission electron microscopy (TEM) and Raman spectroscopy (RS) measurements have been carried out. It was confirmed by both TEM and RS that the particle size and morphology was varying throughout the film. For most of the samples, nanoparticles seemed to be mixed in size but the general tendency is to have smaller size distributions from central part to the outer part of the films. Formation of crystalline structures was confirmed by X-Ray diffraction (XRD) with Si(111) peaks. It was also shown by photoluminescence spectroscopy (PL) that the optical emission was in the visible range and shifts with respect to size difference of Si-NCs. Size distribution as a function of PL emission energy has been demonstrated for particles less than 8nm. TEM was employed to investigate the size distribution of the larger particles which was around 50nm. The responsible mechanism in the plasma leading to a systematic change on the particle size was discussed by means of electron and ion density, and particle residence time. Getting a good control on the plasma conditions and particle size makes it possible for manipulating Si-NCs to higher packing densities in thin films which makes them suitable for photovoltaic devices such as down converters based on multi-exciton-generation (MEG).