Miniature InGaN-based LEDs operating at a wavelength of 672 nm with an external quantum efficiency of 9.1% fabricated on a GaN template layer

Modern application trends for the development of RGB displays with a high color rendering index (CRI) require light-emitting diode (LED) display technology with greater miniaturization and efficient LEDs operating at deep red wavelengths greater than 650 nm. Although InGaN-based LEDs have achieved high miniaturization performance, efforts to obtain deep-red emission by increasing the indium content introduce a number of factors limiting optical performance, such as high in-plane stress, high dislocation densities, and phase separation. The present work addresses this issue by fabricating deep-red emitting InGaN-based LEDs on an underlying GaN template layer grown from hexagonal GaN column structures formed on a porous SiNx masking layer and coalesced in situ as an underlying layer with significantly reduced internal stresses and dislocation densities. As a result, the fabricated miniature LEDs obtain an external quantum efficiency of 9.1% and a peak wavelength of 672 nm at a current density of 0.4 A/cm2. Accordingly, this work confirms the potential for fabricating InGaN-based LEDs to achieve high-CRI mini/micro RGB displays.