Toward Quantitative Electrochemical Nanomachining of III-Nitrides

In this paper, a comprehensive quantitative investigation is conducted on III-N electrochemical nanomachining to explore the underlying mechanisms. An electric circuit model is proposed for the etching system to interpret the various distinct etching dynamics. Factors such as the geometry of patterning, charge transfer and mass transport properties are taken into consideration as nonlinear lumped elements, which compete for voltage with the GaN/electrolyte interface during etching, thus change the etching behaviors. Quantitative study of nanoporous morphologies suggests that the anodic etching is driven by net voltage bias on the GaN/electrolyte interface and the high electric field in GaN, both related to the generation of charge carrier holes. And by three-dimensional analysis of the electrical field, the etching phase diagram is reconstructed. This study not only offers a mechanistic understanding of GaN anodic etching, but also provides a systematical prospective in constructing nanostructures on a broad range of semiconductor materials using electrochemical method.