Self-organized GaN nanotips for cold cathode application

We investigated self-organized GaN nanotips for the cold cathode application, which was fabricated by reactive ion etching (RIE). The density of the nanotips fabricated by RIE was approximately 2 × 10 cm^-2. Its height was approximately 200 nm. It is observed that the distribution of the nanotips fabricated on epitaxial lateral over growth (ELO) GaN is uniform in spite of window and mask region on ELO GaN surface. This fact supports that the formation mechanism of nanotips is attributed to a masking effect of nanometer-scale SiO₂ masks not to the threading dislocations in the GaN layer. Field emission from the GaN nanotips was observed. The current I was 1 μA at 900 V. The field enhancement factor βd, which is related to the top structure of the emitter and is the product of the field conversion factor β and the sample-anode gap d, was estimated to be 460 from the Fowler-Nordheim (F-N) plot.