GaN nanotip pyramids formed by anisotropic etching

We experimentally demonstrate the formation of GaN nanotip pyramids by selective and anisotropic etching of N-polar GaN in KOH solution. For samples grown with adjacent Ga- and N-polar regions on the same wafer, the KOH solution was found to selectively etch only the N-polar surface while leaving the Ga-polar surface intact. An aggregation of hexagonal pyramids with well defined {10 (1) over bar (1) over bar} facets and very sharp tips with diameters less than similar to20 nm were formed. The density of the pyramids can be controlled by varying the KOH concentration, solution temperature or the etch duration. The GaN etching activation energy is estimated to be E(a)approximate to0.587 eV. Dense GaN pyramids with sharp tips have applications in both electronic and photonic devices. (C) 2003 American Institute of Physics.