Mechanisms of enhanced light emission in GaN-based light-emitting diodes by V-shaped micropits

Abstract : We have investigated the light emission mechanisms of V-shaped, hexagonal-micropit-arranged, InGaN/GaN light-emitting diodes (HMA-LEDs). By near-field scanning optical microscopy and the confocal scanning electroluminescence microscopy, we found that enhanced light output of HMA-LED was significantly contributed by not only improved light-extraction efficiency but also locally improved crystalline quality near the micropit. Etch pit density and cross-sectional transmission electron microscope image indicate that threading dislocation (TD) bending lead to decrease the TD density near the micropit. Furthermore, partially linearly polarized light from the inclined facets of the HMA-LEDs was observed.