Side wall wet etching improves the efficiency of gallium nitride light emitting diodes

This paper describes a method for introducing side wall etching (SWE) into the process flow for the fabrication of light emitting diodes. We investigated the effect of the deposition conditions for the SiO ₂ protection layer on the surface damage of devices during the wet etching process and, thereby, the electrical characteristics of the device performance. More importantly, we found that recording X-ray diffraction spectra prior to SWE processing allowed us to categorize the quality of the GaN epiwafers in terms of the full width at half maximum of the signal for the (102) facet, thereby allowing optimization of the etching time to avoid both over-and under-etching and potentially increasing the production yield and the reliability of the device performance. From a comparison of the electrical and photonic characteristics of devices prepared with and without SWE processing, we found that the former exhibited superior performance, with no degradation of the electrostatic tolerance or reliability, relative to the latter.