Pit Formation, Patterning and Flattening of Ge Surfaces in O₂-Containing Water by Metal-Assisted Chemical Etching

Metal-assisted chemical etching is a novel method of etching a Ge surface in contact with a noble metal in water. Its basic mechanism involves the catalytic activity of metals to reduce dissolved O2 molecules in water, which accompanies the formation of a soluble oxide (GeO2) on the Ge surface around the metal. Here, we apply this electroless etching to the pit formation, nanoscale patterning and surface flattening of Ge. The fundamental etching properties for these three processes are also presented.