ABSTRACT
Electrochemical porosification is a frequently used method to realize semiconducting nanostructures. The advantages of the method are simplicity, compatibility with the CMOS process, ability to control the morphology of the porous layers, and preservation of the long-range crystalline order in the resulting nanostructures. The porous Silicon (PGe) was discovered in 1956 by Arthur Uhlir Jr. and Ingeborg Uhlir from Bell Labs while developing the process to polish and to texture the surface of Si and Ge. The unique feature of PGe is that its morphology depends on the applied current density and the passivation degree, allowing to change the morphology on the fly and to engineer complex multilayer nanostructures. In order to get further insight into the structural properties of the fabricated meso-PGe layers, micro-Raman scattering spectroscopy measurements were carried out. Bipolar electrochemical etching, which consists of periodical switching from cathodic to anodic bias during the etching process, is a powerful tool to form mesoporous Ge layers with controlled morphology.
