The surface recombination velocity at clean and modified Si(1 0 0)2 x 1, Si(1 1 1)-1 x 1 and Si(1 1 1)-7 x 7 surfaces was studied with the pulsed photoluminescence technique. High resolution electron energy loss spectroscopy and low energy electron diffraction were employed to correlate the surface recombination velocity to the chemical bonds at the surface and the surface morphology. Passivation of surface dangling bonds by the chemisorption of water and maleic anhydride shows that the surface dangling bonds are not recombination active. In contrast, we observe that the introduction of oxygen or carbon atoms into Si backbonds causes the generation of non-radiative recombination centres. (C) 2002 Elsevier Science Ltd. All rights reserved.