Direct Epitaxial Approach to Achieve a Monolithic On-Chip Integration of a HEMT and a Single Micro-LED with a High-Modulation Bandwidth

Visible light communications (VLC) require III-nitride visible micro-light-emitting diodes (mu LEDs) with a high-modulation bandwidth. Such mu LEDs need to be driven at a high injection current density on a kA/cm(2) scale, which is about 2 orders of magnitude higher than those for normal visible LED operation. mu LEDs are traditionally fabricated by dry-etching techniques where dry-etching-induced damages are unavoidable, leading to both a substantial reduction in performance and a great challenge to viability at a high injection current density. Furthermore, conventional biasing (which is simply applied across a p-n junction) is good enough for normal LED operation but generates a great challenge for a single mu LED, which needs to be modulated at a high injection current density and at a high frequency. In this work, we have proposed a concept for an epitaxial integration and then demonstrated a completely different method that allows us to achieve an epitaxial integration of a single mu LED with a diameter of 20 mu m and an AlGaN/GaN high-electron-mobility transistor (HEMT), where the emission from a single pLED is modulated by tuning the gate voltage of its HEMT. Furthermore, such a direct epitaxial approach has entirely eliminated any dry-etching-induced damages. As a result, we have demonstrated an epitaxial integration of monolithic on-chip mu LED-HEMT with a record modulation bandwidth of 1.2 GHz on industry-compatible c-plane substrates.

Automated summary

The study introduces a concept for epitaxial integration and demonstrates a novel method to achieve epitaxial integration of a single mu LED with an AlGaN/GaN high-electron-mobility transistor (HEMT), eliminating dry-etching-induced damages and successfully fabricating on-chip mu LED-HEMT with a record modulation bandwidth of 1.2 GHz on industry-compatible substrates.