Review of a direct epitaxial approach to achieving micro-LEDs

There is a significantly increasing demand of developing augmented reality and virtual reality (AR and VR) devices, where micro-LEDs (mu LEDs) with a dimension of <= 5 mu m are the key elements. Typically, mu LEDs are fabricated by dry-etching technologies, unavoidably leading to a severe degradation in optical performance as a result of dry-etching induced damages. This becomes a particularly severe issue when the dimension of LEDs is <= 10 mu m. In order to address the fundamental challenge, the Sheffield team has proposed and then developed a direct epitaxial approach to achieving mu LEDs, where the dry-etching technologies for the formation of mu LED mesas are not needed anymore. This paper provides a review on this technology and then demonstrates a number of monolithically integrated devices on a single chip using this technology.