Neutral anodic etching of GaN for vertical or crystallographic alignment

摘要

Etching of gallium nitride for various device applications has attracted much attention; however, previous reports have all been performed in acidic or basic etchant solutions. Herein, we demonstrate how neutral electrolytes such as NaNO_3 or NaCl can be used to rapidly etch n-GaN electrochemically and achieve a porous structure that is either vertically aligned or faceted according to the GaN crystallography, in NaNO_3 and NaCl, respectively. It is demonstrated that the etching properties of NaNO_3 and HNO_3 are very similar, showing that the etching process in this system is surprisingly insensitive to pH. This neutral-pH process enables safer and greener GaN etching, as well as opening up the possibility of crystallographic etching of GaN using an anodic process.