Compositions useful for the selective removal by etching of silicon-germanium-containing materials relative to silicon-containing materials, from a microelectronic device having features containing these materials at a surface, the compositions containing hydrofluoric acid, acetic acid, hydrogen peroxide, and at least one additional acid that will improve performance as measured by one or more of an etching rate or selectivity and are tunable to achieve the required Si:Ge removal selectivity and etch rates.