Ultrasharp periodic AlN nanotips formed via purely subtractive nanofabrication

Ultrasharp periodic AlN structures hold promise for applications such as the housing of site-controlled quantum dots and field emission structures. Etching could be an effective route to achieve this since it avoids the genera- tion of unwanted point defects resulting from dry etching or regrowth under unoptimised conditions. However, exploration of wet etching of AlN to create uniform arrays of periodic nanostructures has thus far been limited. In this paper, a combination of initial dry etching of a 2D AlN template followed by wet chemical etching is performed to reveal periodic arrays of nanostructures. A study of different initial dry etched structures and wet etching times were performed resulting in periodic arrays of ultrasharp AlN nanopyramids. It was discovered that potentially unconventional inclined facets were realised. A model to describe the dynamics of the wet etching on the dry etched nanostructures is also proposed.