Wurtzite P-doped GaN triangular microtubes as field emitters

Novel P-doped GaN triangular microtubes were synthesized by a facile chemical vapor deposition method. This novel structure consists of a single hexagonal wurtzite phase with a triangular cross section. The tube lengths range from tens of to several hundred micrometers, and each side has a width between 0.5 and 1 μm, with a tube wall thickness of several tens of nanometers. The formation mechanism of this triangular tubular structure is a vapor-solid methanism, as determined by electron microscopy. Extraordinary and stable infrared emission (centered at ∼724 nm) from the P-doped GaN triangular microtubes was observed from their photoluminescence spectroscopy. The low turn-on field (2.9 V μm^-1), high field-enhancement factor, large current density (3 mA cm^-2 at a field of ∼9.5 V μm ^-1), and high stability indicate the suitability of P-doped GaN microtubes as potential field emitters. This field emission property is attributed to the specific crystallographic feature-the rigid triangular structures with effective P doping and rough surface hillocks.