Improved Wavelength Stability of InGaN-Based Red LEDs Grown on Graphene/SiC Substrates

Abstract

The application of InGaN based red LEDs in Micro LED display has been severely limited due to their low luminous efficiency and poor wavelength stability. In this work, we demonstrate InGaN based red LEDs with improved wavelength stability on SiC substrates. The key of our method is to introduce a graphene intermediate layer between the epitaxial LED structure and SiC substrate. Another important process is to modulate the growth behavior and stress state of the GaN film and LED structure on graphene. This is achieved by optimizing the nitrogen-plasma pre-treatment time of graphene. As a consequence, InGaN based red LEDs with small wavelength shift with the change of driving current are obtained. The wavelength shift is 8 nm as the forward driving current density increase from 1 to 10 A/cm2, which is significantly lower than the 25 nm of the reference red LEDs directly grown on SiC substrates. In addition, we analyse the mechanism responds to the improvements of wavelength stability for the red LEDs grown on graphene/SiC. This work provides a feasible approach for enhancing the wavelength stability of InGaN based red LEDs.