Surface Structure-Controlled Monolithic Multiple Color Semipolar GaN-based Light-Emitting Diodes

In this study, monolithic red, green, and blue emission semipolar (11-22) GaN-based light-emitting diodes (LEDs) were developed using the SiO2 hexagonal pattern epitaxial lateral overgrowth (HPELO) technique. We found that the semipolar HPELO GaN film can significantly increase the arrowhead-like surface (ALS) structure, which can distribute the indium incorporations of the InGaN active layer. Because of the relatively thick lateral overgrowth technique used in the HPELO semipolar GaN template, its ALS structure is found to be much larger than that of the conventional semipolar GaN/m-sapphire template. The indium composition of the InGaN active layer grown on the semipolar HPELO GaN template is higher than that of the conventional GaN template because the crystallographic planes of the ALS structure have a higher indium incorporation rate than the semipolar (11-22) plane, resulting in a longer emission wavelength for the semipolar HPELO GaN-LEDs. Therefore, an emission wavelength from semipolar HPELO GaN-LEDs can be significantly blue-shifted because of the strong band-filling effect at different indium incorporations within the ALS structure. Thus, semipolar HPELO GaN-LEDs can be applied to achieve amber to blue emission for monolithic multi-color emitters.