Electrochemical Prediction Tool of Porous GaN Morphology

We report a systematic electrochemical study that allows fine-tuning of the pore formation process in gallium nitride (GaN). We have investigated several parameters of pore formation, as they are commonly reported, such as the doping level of n-GaN, the applied potential, the type, and the concentration of the electrolyte. Our work goes a step further by identifying the electrochemical signature of the dominant mechanisms. It was found that a wide range of porous morphologies can be obtained, branched or tubular porous structures, from low pore density with large average pore size to high pore density with small pore size. It is possible to describe the mechanism of pore propagation in GaN as a competition between different kinetics: the kinetics of hole formation in the semiconductor and the kinetics of GaN oxide formation and dissolution. In this work, we highlight the relationship between the shape of the chronoamperometry plots and the mechanisms influencing pore morphology. This correlation allows for the use of chronoamperograms as a predictive tool for pore morphology in porous GaN.