This paper presents the results of PL spectrum studies for Si nano-crystallites embedded in amorphous silicon matrix. Investigated layers were deposited by the hot-wire CVD method on glass substrates at the wafer temperature 300°C and different filament temperatures from the range 1650-1950°C. It was shown that variation of temperatures of filament (hot-wire) allows to produce the films with desirable parameters. Using of X-ray diffraction and photoluminescence methods the correlation between some photoluminescence bands and the sizes of Si nano-crystallites as well as the amorphous phase volume was shown. The nature of light emission is discussed.