Substrates with a modulated surface texture were prepared by combining different interface morphologies. The spatial frequency surface representation method is used to evaluate the surface modulation. When combining morphologies with appropriate geometrical features, substrates exhibit an increased scattering level in a broad wavelength region. We demonstrate that the improved scattering properties result from a superposition of different light scattering mechanisms caused by the different geometrical features integrated in a modulated surface texture. © 2010 American Institute of Physics. ͓doi:10.1063/1.3488023͔ Light-trapping is an essential approach in thin-film silicon solar cells to increase the effective optical path in thin absorber layers. It uses scattering of light at rough interfaces, introduced into the solar cell by means of substrates coated with a randomly surface-textured transparent-conductiveoxide ͑TCO͒ layer. 1 The multijunction approach is widely used in these solar cells. 2,3 Employing different absorber materials in multi-junction solar cells, such as amorphous silicon alloys and microcrystalline silicon, efficient light trapping is required at long wavelengths ͑up to 1100 nm͒. To meet this demand, TCO substrates with different surface textures have recently been developed and tested in solar cells, such as optimized wet-etched 4 or surface plasma-treated 5 zinc-oxide, double-textured tin-oxide, 6 and a combination of etched glass with zinc-oxide. 7 Even though the potential of using of high performance TCOs has been already investigated, 8 a physical explanation of why these textures result in high scattering properties is still missing.In this paper we introduce and analyze a more general concept of surface textures for enhanced scattering in a broad wavelength range, namely a modulated surface texture. We demonstrate that the enhanced scattering is achieved by superposition of different scattering mechanisms caused by the different geometrical features integrated in a modulated surface texture.A substrate with a modulated surface texture can be prepared as a stack of layers in which a different texture is introduced at individual interfaces. Provided the layers are thin enough the textures of the individual interfaces are transferred to a subsequent interface. The resulting surface of the stack accommodates all the morphological components introduced at the individual interfaces. The stack may comprise layers of the same or different materials and a broad range of lateral and vertical geometrical features introduced at interfaces. By combining appropriate geometrical features introduced at the individual interfaces one can take advantage of superimposing the scattering mechanisms caused by these different geometrical features and achieving higher scattering levels in a broad wavelength range in comparison to the scattering contributions from individual morphologies.When the geometrical dimensions of the rough surface are larger than the wavelength of light, the scattering with strongly d...