Authors: C-C Hsieh, W-C Ke, N-P Chen, W-J Lin, Y-C Cheng, T-C Li, J-C Lin
Affilation: Yuan Ze University, Taiwan
Pages: 249 - 252
Keywords: gallium nitride, pyramid array, fabrication
GaN has relatively high refractive index and results in low light extraction efficiency in photonics applications. A novel way to combine the various methods to enhace the efficiency is to construct a pyramid array on the GaN surface. Not only does it have the periodic structure, it also has an effective index of refraction with gradient value along the height of the pyramid. An n-type GaN wafer of (0001) plane (c-plane) is used herein to demonstrate the method of fabricating the pyramid array. A layer of SiO2 as an etching mask is grown on top of GaN by plasma enhanced chemical vapor deposition (PECVD). The layer gets its array pattern defined by E-beam writer and the associated photoresist and then gets etched by high density plasma (HDP). Then, the GaN wafer with the completed SiO2 mask undergoes inductively coupled plasma (ICP) etching. By varying the etching rate and the mask layer thickness, we can obtain different shapes of pyramids. The study investigates various factors affecting the array outcomes, with several array sizes and pitches. The technique can be employed to GaN layers in photonics devices to have arrays with desired pitch and size for optimal performance in different applications.