NOVELTY - Aqueous alkaline composition comprises: (A1) at least one quaternary ammonium hydroxide; (B1) at least one component that consists of (b1) water-soluble sulfonic acids (I), (b2) water-soluble phosphonic acids (II), (b3) water-soluble sulfuric acid esters (III), (b4) water-soluble phosphoric acid esters (IV), or (b5) water-soluble phosphoric acid esters (V); and buffer system, where at least one component other than water is volatile.    USE - The aqueous alkaline composition is useful for treating the surface of silicon substrates and manufacturing devices comprising photo-voltaic cells and solar cells (all claimed).    ADVANTAGE - The aqueous alkaline composition exhibits high cleaning efficiency so that the formation of haze and re-contamination of the surfaces of the silicon substrates were avoided; exhibits strong hydrophilizing effect so that the resulting hydrophilic surface is exceptionally well wetted with highly polar spray-on emitter sources (aqueous or alcoholic phosphoric acid) so that the doping and the formation of the emitters could be controlled precisely; has stable pH or only a slight decrease or increase of its pH during the bath lifetime and provides highly efficient solar cells.    DETAILED DESCRIPTION - Aqueous alkaline composition comprises: (A1) at least one quaternary ammonium hydroxide; (B1) at least one component that consists of (b1) water-soluble sulfonic acids and their salts of formula (R1SO3-)nXn+ (I), (b2) water-soluble phosphonic acids and their salts of formula RPO32-(Xn+)3-n (II), (b3) water-soluble sulfuric acid esters and their salts of formula (ROSO3-)nXn+ (III), (b4) water-soluble phosphoric acid esters and their salts of formula ROPO32-(Xn+)3-n (IV) or (b5) water-soluble phosphoric acid esters and their salts of formula ((RO)2PO-)nXn+ (V); and a buffer system, where at least one component other than water is volatile.    n=1 or 2;    X=H, ammonium, alkaline metal or alkaline-earth metal;    R=R1 or alkylaryl (where aryl is benzene or naphthalene and alkyl is methylene, ethanediyl or propanediyl); and    R1=2-5C aliphatic or 4-6C cycloaliphatic (both having at least one olefinically unsaturated double bond).    The P atom in (II) is bonded directly, and the S atom in (III) and the P atom in (IV) and (V) are each bonded via O atom to an aliphatic carbon atom).    INDEPENDENT CLAIMS are also included for:    (1) treating (M1) surface of a silicon substrate, comprising providing the aqueous alkaline composition, contacting at least one major surface of the silicon substrate at least once with the aqueous alkaline composition to obtain a clean hydrophilic surface, and removing the major surface from the contact with the aqueous alkaline composition;    (2) a method (M2) for manufacturing devices generating electricity upon the exposure to electromagnetic radiation, comprising:    (a1) texturing at least one major surface of the silicon substrate with an etching composition, thus generating a hydrophobic surface,    (a2) hydrophilizing the hydrophobic surface by employing the method (M1),    (a3) applying at least one spray-on emitter source onto the hydrophilic surface,    (a4) heating the silicon substrate contacted with the emitter source, thus forming emitters within the silicon substrate or emitters within the silicon substrate and a silicate glass on top of the surface of the silicon substrate,    (a5) modifying the upper layer of the silicon substrate containing the emitters or removing the silicate glass from the surface of the silicon semiconductor thus obtaining a hydrophobic surface,    (a6) hydrophilizing the hydrophobic surface by employing the method (M1),    (a7) depositing an antireflective layer on top of the modified upper layer of the silicon substrate containing the emitters, thus obtaining an intermediate and    (a8) further processing the intermediate to obtain the device, where the step (a2) and/or (a6) is carried out; or    (b1) step (a1) as above per se,    (b2) treating the hydrophobic surface of the silicon substrate in a heated atmosphere containing at least one gaseous emitter source, thus forming emitters within the silicon substrate or emitters within the silicon substrate and a silicate glass on top of the surface of the silicon substrate, and    (b3) steps (a5), (a7) and (a8) as above per se; and    (3) use of the buffer system, where at least one component other than water is volatile for stabilizing the pH of aqueous alkaline composition containing (A1), and (B2) at least one component that consists of (b9) water-soluble sulfonic acids and their salts of formula (RSO3-)nXn+ (Ia), (b2), (b3), (b4) or (b5).