Synchrotron-radiation-induced wet etching of germanium

A room-temperature photoinduced chemical wet etching process for Ge wafers using x rays from a synchrotron radiation source is described. De-ionized water and H2O:HNO3 solutions were used as etchants. This process produces smoothly etched Ge surfaces with a root-mean-square surface roughness of a few angstroms. Etching chemistry and etching conditions, such as x-ray beam sizes, solution concentration, and doping type, are discussed.