Numerical analysis of the influence of sidewall defects on AlGaN-based deep ultraviolet micro-light emitting diodes

Abstract

The optoelectronic performance of AlGaN-based deep ultraviolet micro-light emitting diodes are strongly affected by surface recombination at the mesa sidewall. Herein, the influence of sidewall defect density and location changes on the photoelectric properties and carrier recombination mechanisms were theoretically investigated. The results indicate a significant deterioration in the internal quantum efficiency and optical power with an increase in the sidewall defect density at the edge of the LED mesa. This deterioration is attributed to the Shockley-Read-Hall nonradiative recombination caused by sidewall defects. The sidewall defects also act as traps for electrons and holes, significantly affecting the carrier injection capability. Furthermore, the position dependence of carrier concentration and recombination rate along the lateral dimension of the LED mesa were studied. The results show that etching process not only causes sidewall damage but can damage the quality of internal epitaxial materials. These effects should be minimized by optimizing the dry-etching process.