In the present paper, we report on thin-film microcrystalline silicon solar cells grown at high deposition rates on back-reflectors with optimized light-scattering capabilities. A single-junction solar cell with a conversion efficiency of η = 7.8% (2 μm thickness) was fabricated at a deposition rate of 7.4 angstroms/s. Another microcrystalline cell was successfully implemented in a `micromorph' tandem (i.e. a microcrystalline/amorphous tandem cell with n-i-p-n-i-p configuration); the resulting initial conversion efficiency was η = 11.2%. A 4 μm thick single-junction cell at a deposition rate of 10 angstroms/s and with a conversion efficiency of η = 6.9% was fabricated on a non-optimized substrate. Special attention is drawn to near-infrared spectral response and interface optimization.