A Study of the Etching Rate of Single-Crystal Germanium

A study has been made of the rate at which single‐crystal germanium is etched under various conditions. For simplicity, the principal etchants used were composed of only , , and water. Data are given for the rate as a function of temperature and composition of the etchant, and as a function of the orientation and impurity content of the crystal. An equation which assumes two reactions taking place in sequence on the surface fits the rate vs. temperature data within the limits of experimental error. In the range studied, the rate‐controlling processes are sensitive to sample orientation. From etching data, a value was obtained for the thickness of the disturbed surface layer due to abrasive grinding. This was found to be in the range of 2–10 μ and to depend on sample orientation and abrasive particle size. Comparative data are given for two common etchants of a more complicated composition.