Demonstration of ultra-small 5 × 5 μm2 607 nm InGaN amber micro-light-emitting diodes with an external quantum efficiency over 2%

Abstract

Red micro-size light-emitting diodes (μLEDs) less than 10 × 10 μm2 are crucial for augmented reality (AR) and virtual reality (VR) applications. However, they remain very challenging since the common AlInGaP red μLEDs with such small size suffer from a dramatic reduction in the external quantum efficiency. In this work, we demonstrate ultra-small 5 × 5 μm2 607 nm amber μLEDs using InGaN materials, which show an EQE over 2% and an ultra-low reverse current of 10−9 A at −5 V. This demonstration suggests promising results of ultra-small InGaN μLEDs for AR and VR displays.

Demonstration of 621-nm-wavelength InGaN-based single-quantum-well LEDs with an external quantum efficiency of 4.3% at 10.1 A/cm2

“…LEDs in the red spectral range. 16,18,23,33 However, we found additional emission peaks in the blue spectral range with increasing current injection, as shown in Fig. 2(c).…”

“…4(b). 16,18,20,21,23,26,33,[37][38][39][40][41] We also calculated the EQEs and WPEs of the LEDs at various injection currents, as shown in Fig. 5.…”

“…14,15 These issues with the optical properties manifest as large peak wavelength shifts and reduced internal quantum efficiencies (IQEs). [16][17][18] Several approaches have been proposed to mitigate the lattice mismatch between InGaN active regions and their underlying layers. These presume that the crystalline quality of the InGaN active region can be improved because the growth temperature increases due to In pulling effect.…”

“…However, the EQEs of even the state-of-the-art InGaN-based red LEDs are so far from that of typical blue and green LEDs. 16,18,21,26 Due to its high-In-content, the InGaN active layer for red emission has fundamental issues, including a large QCSE and poor material quality.…”

Progress of InGaN-Based Red Micro-Light Emitting Diodes

“…Micro-size light-emitting diodes (µLEDs) have attracted huge attention as the nextgeneration display technology for wide applications, such as wearable watches, virtual/augmented reality, micro-projectors, and ultra-large televisions [1][2][3][4]. InGaN-based red µLEDs have become the research focus now [5][6][7][8]. To achieve red emission, the indium composition in the InGaN quantum wells (QWs) should be greater than 35%, which causes a lot of challenges.…”