High Q factor Electrically Injected Green Micro Cavity

Abstract

Green micro-cavity (MC) with a quality factor (Q) exceeding 6000 was demonstrated under current injection. The MC consists of two dielectric distributed Bragg reflectors (DBRs) and InGaN/GaN quantum wells (QWs) in between. To form a lateral optical confinement (LOC) structure, a low-index thin AlN layer was used to replace part of the p-GaN. The device showed multi-longitudinal mode emission, from 460 to 540 nm, and higher-order lateral confined modes were clearly observed. By optimizing the cavity fabrication processes and lateral optical confinement, the linewidth of resonant mode is as narrow as 0.082 nm, indicating a high Q value of 6039 in green spectral region. This is the highest value in electrically injected GaN-based MC to the best of our knowledge. In addition, three-dimensional (3D) confined optical states were observed and studied via angle resolved measurement for the first time in an electrically injected GaN-based MC. The emission characteristics of devices as a function of cavity length, as well as the loss mechanism inside the cavity were also systematically analyzed.