Nanocrystalline silicon films are prepared by plasma enhanced chemical vapour deposition of silane under the conditions of high hydrogen dilution (3:100). The film structure consists of nanoclusters 0.8 to 5 nm in size (volume fraction 30%) embedded in an amorphous matrix. The Taue gap of the amorphous matrix is 1.95 to 2.05 eV depending on deposition parameter. These films are characterized as regards photoluminescence (PL) and, prepared to p-i-n structures, electroluminescence (EL). The PL and EL agree in (i) luminescence peak at 1.9 eV, i.e. small Stokes shift, (ii) almost no temperature dependence between 77 K and 293 K, (iii) fast kinetics with time constant of a few 10−8 s. These data can be understood in terms of quantum confinement in Si nanocrystallites smaller than around 2 nm. The EL in addition exhibits a luminescence band extending up to 3 eV, which can be interpreted by interband transition due the hot carriers.