New Method of Porous Ge Layer Fabrication: Structure and Optical Properties

Porous germanium films were produced by selective removal of the GeO 2 matrix from the GeO 2 heterolayer in deionized water or HF. On the basis of Raman and infrared spectroscopy data it was supposed that a stable skeletal framework from agglomerated Ge nanoparticles (amorphous or crystalline) was formed after the selective etching of GeO 2 heterolayers. The kinetics of air oxidation of amorphous porous Ge layers was investigated by scanning ellipsometry. Spectral ellipsometry allowed estimating the porosity of amorphous and crystalline porous Ge layers, which was ~70 and ~80%, respectively.