Growth, characterization, and application of well-defined separated GaN-based pyramid array on micropatterned sapphire substrate

We tried to obtain microstructures on a three-dimensional (3D) micropatterned substrate by laser drilling. The influences of the dimensions of the drilling holes on the morphology and the material quality of the grown structures were studied. Uniform micropyramid arrays with relatively low dislocation density can be achieved by adjusting the laser drilling parameters. The internal quantum efficiency was estimated to be improved by a factor of 3 for a pyramid structure compared with that of planar LEDs. We fabricated 5 x 7 mm(2) flexible LEDs employing the pyramid structure and the devices exhibited good flexibility without performance reduction after bending. (C) 2017 The Japan Society of Applied Physics