III-nitride photonic crystals

We report the achievement of nanofabrication and characterization of a triangular lattice array of photonic crystals (PCs) with diameter/periodicity as small as 100/180 nm on an InGaN/GaN multiple quantum well using electron-beam lithography and inductively coupled plasma dry etching. Optical measurements of the PCs performed using near-field scanning optical microscopy showed a 60° periodic variation with the angle between the propagation direction of emission light and the PCs lattice. An unprecedented maximum enhancement factor of 20 was obtained for the emission light intensity at wavelengths as short as 475 nm at room temperature with emission light parallel to the $Γ–K$ direction of the PCs lattice. The implications of these results to nitride-based optoelectronic devices, particularly in improving the light extraction efficiency in light-emitting diodes both for blue/green as well as UV emitters, are discussed.