Observations of Macroporous Gallium Nitride Electrochemically Etched from High Doped Single Crystal Wafers in HF Based Electrolytes

In this paper, we present a process to produce porous structures by electrochemical etching of highly doped n-type GaN single crystals in aqueous HF solutions. At first, we show that we are able to perform well oriented macropores from 30% HF based solutions. To our knowledge, it’s the first time that this morphology is observed in porous GaN. These macropores grow from a 5 μm thick mesoporous layer observable at the sample surface. No significant difference in term of morphology is visible for etching on Ga or N face. Moreover, the influence of the HF concentration on the morphology is also discussed.