Silicon nanocrystals (Si-NCs) draw attention since they exhibit size dependent luminescence, improved charge storing capacity and increased surface reactivity. For instance, the size dependent optical properties of Si-NCs show great promise for increasing the efficiency of solar cells. Si-NCs could be used as spectrum down converters by converting the excess energy of a hot photon to generate multiple exciton pairs. For successful applications, the main issues on Si-NC synthesis are size control and surface engineering for improved optical properties, and high throughput. Among these points, the amount of throughput is highly critical for large scale applications however, it is not possible to achieve with current production techniques. Our research goal is to show that it is possible to fulfill these demands with a novel route by using the remote expanding thermal plasma (ETP) technique. Synthesis of Si-NCs in a remote Ar/SiH₄ plasma occurs by means of a reaction sequence of ion-SiH₄ charge exchange and subsequent addition of SiH₄ molecules. This realizes spontaneous and nearly complete conversion of SiH₄ into Si-NCs with very high throughputs of about 25mg/min, the fastest deposition rate reported in the literature so far. Moreover, ETP has the freedom of tuning the size of the Si-NCs by controlling the flow rates of SiH₄ and Ar, i.e. the residence time in the plasma. Synthesized Si-NCs have a bimodal distribution of small (4-7nm) and large (50-80nm) sizes as confirmed by TEM, which is a consequence of the plasma expansion and reactor geometry. Bimodality has been analyzed with Raman spectroscopy by studying the asymmetry and shift in the transverse optical vibration mode of bulk-Si at 521cm^-1. Photoluminescence spectroscopy confirms the presence of monodisperse size distribution of small Si-NCs (4-7nm) leading to luminescence in the region 600-900nm. Observation of luminescence illustrates the quality of the nanocrystal surface passivated by the rapid native oxidation. Preliminary results show separation of the bimodal distribution can be controlled by means of geometrical isolation of the regions, in which small and large particles are formed.