I would like to know if someone can recommend a simple etchant/cleaning process for (100) Si (that will not etch Si - very important as there is a nipi superlattice on one face) but will remove the following sputtered (~100-nm thick) metallic films from the Si surfaces: Nb (100-nm), Cr\Au pads (10-nm\100-nm), and Al (100-nm). I will find out soon if a piranha clean will do the trick but just in case ... thanks. Thomas