Nanotip GaN pyramids formed by polarity-selective chemical etching

In this paper we have systematically studied the chemical etching of Ga and N-polar GaN with KOH, varying as a parameter either the concentration or the temperature of the solution for a fixed etch duration. The growth polarity can be controlled by the deposition of an appropriate buffer layer during molecular beam epitaxy (MBE). Using a patterned template, we grown samples with adjacent Ga-and N-polar regions. The N-polar GaN was found to be selectively etched while the Ga-polar GaN remained intact. We have made preliminary measurements of electron field emission from the GaN nanotip pyramids. Anode was suspended 50-500μm above the film and I-V measurements were made at 50μm increments.