The effect of small addition of disilane on highly diluted silane in hydrogen discharges for the deposition of microcrystalline silicon thin films has been investigated. A spectacular six times enhancement of the film growth rate has been recorded by introducing 0.6% disilane in the mixture at very low power densities. It is clarified that the observed increase is not a result of the higher concentration of silicon atoms in the gas feed but it can rather be attributed to the increase of silane dissociation caused by the addition of disilane and to the enhanced contribution of higher radicals to the film growth. The effect of the small addition of disilane on the film growth along with the rationalistic use of the silicon precursors need to be further examined as a solution for rapid deposition of microcrystalline silicon layers. (C) 2003 Elsevier B.V. All rights reserved.