High‐Efficiency InGaN Red Mini‐LEDs on Sapphire Toward Full‐Color Nitride Displays: Effect of Strain Modulation

Abstract

InGaN red light emitting diode (LED) is one of the crucial bottlenecks that must be broken through to realize high-resolution full-color mini/micro-LED displays. The efficiency of InGaN LEDs drops rapidly as the emission spectra go from blue/green to red range due to the poor quality of high-indium-content InGaN materials. Here, high-performance InGaN red LEDs on sapphire grown by metal-organic chemical vapor deposition through strain modulation are reported. A composite buffer layer is proposed to increase the surface lattice constant of GaN and hence successfully enhances the indium incorporation efficiency of the following InGaN active layers. Consequently, a highefficiency InGaN red mini-LED chip (mesa area: 100 × 200 µm 2 ) with a peak wavelength of 629 nm and an external quantum efficiency of 7.4% is realized. Finally, a full-color nitride mini-LED display panel with 74.1% coverage of Rec.2020 color gamut by using the InGaN red mini-LED chips is fabricated. The study signifies the great potentials of full-nitrides high-resolution fullcolor mini/micro-LED displays.

Recent advances in micro-pixel light emitting diode technology

“…In another study on strain modulation, Chen et al 166 optimized the thickness of a low-temperature GaN buffer layer. They found that a thickness of 7 nm produced the highest indium content in the QW, resulting in a peak EQE of about 7.4% at a wavelength of 629 nm, with a chip size of 100 Â 200 lm 2 .…”

Recent Progress in Long‐Wavelength InGaN Light‐Emitting Diodes from the Perspective of Epitaxial Structure

“…Similar to the hybrid NL structure, Chen et al proposed a composite buffer layer consisting of sputter AlN and low-temperature GaN to increase the surface lattice constant of GaN and enhance the indium incorporation efficiency. [27] An efficient InGaN red mini-LED chip with a peak wavelength of 629 nm and an external quantum efficiency of 7.4% was consequently realized.…”

III-Nitride Materials: Properties, Growth, and Applications

“…[30,[37][38][39][40][41][42]. The EQE of InGaN red microLEDs has already reached 7.4%, demonstrating promise for application soon [43,44]. Blue and green InGaN lasers have also achieved inspiring performances [45,46].…”