NOVELTY - The method comprises immersing a crystalline silicon substrate (10) into an aqueous alkaline etchant solution to form a pyramid shaped textured surface on the crystalline silicon substrate with exposed faces (12), where the aqueous alkaline etchant solution comprises an alkaline component and a nanoparticle slurry. The concentration of the alkaline component in the aqueous alkaline etchant solution is 0.5-5 wt.%. The nanoparticle slurry has colloidal particles having the particle size of 10-1000 nm. The concentration of the nanoparticle slurry in the solution is 0.1-5 wt.% on a dry basis.    USE - The method is useful for forming a textured silicon surface of a solar cell (all claimed).    ADVANTAGE - The method is capable of achieving minimal wafer reflectance and increased light absorption of the solar cell.    DETAILED DESCRIPTION - The method comprises immersing a crystalline silicon substrate (10) into an aqueous alkaline etchant solution to form a pyramid shaped textured surface on the crystalline silicon substrate with exposed faces (12), where the aqueous alkaline etchant solution comprises an alkaline component and a nanoparticle slurry. The concentration of the alkaline component in the aqueous alkaline etchant solution is 0.5-5 wt.%. The nanoparticle slurry has colloidal particles having the particle size of 10-1000 nm. The concentration of the nanoparticle slurry in the aqueous alkaline etchant solution is 0.1-5 wt.% on a dry basis. The aqueous alkaline etchant solution further comprises an additive and a surfactant. The concentration of the alcohol in the aqueous alkaline etchant solution is 0.1-20 wt.%. The concentration of the surfactant in the aqueous alkaline etchant solution is 0.00005-0.1 wt.%. The concentration of the pre-etched conditioning silicon in the aqueous alkaline etchant solution is 0.1-1.5 wt.%. The immersing process is performed at 70-90 degrees C. The crystalline silicon substrate has an oriented surface before the immersing process.    DESCRIPTION OF DRAWING(S) - The figure shows schematic cross sectional view of a crystalline silicon substrate.    Crystalline silicon substrate (10)    Exposed faces. (12)