High-Efficiency InGaN-Based Yellow-Green Light-Emitting Diodes

Abstract

We demonstrate the characteristics of high-efficiency yellow-green InGaN-based light-emitting diodes (LEDs) with a strain-accommodative layer and textured surface. The LEDs have chip dimensions of 420×350 µm2 and are packaged in the conventional lamp form. The peak wavelength, optical output power, luminaire efficiency, and external quantum efficiency are 560.7 nm, 0.926 mW, 7.8 lm/W, and 2.1%, respectively, at a driving current of 20 mA. In addition, the output power slope (mW/mA) is 3.3×10-2. It is found that there is potential to improve external quantum efficiency by introducing a chirp InGaN/GaN superlattice structure as the strain-accommodative layer and texturing the surface of the top P-layer in yellow-green InGaN/GaN LEDs. The low power slope can be attributed chiefly to the inferior crystalline quality due to unfavorable growth conditions of InGaN/GaN multiple quantum wells and partially to the stronger internal electric field due to the higher In composition in InGaN wells.

Flower-Like Internal Emission Distribution of LEDs with Monolithic Integration of InGaN-based Quantum Wells Emitting Narrow Blue, Green, and Red Spectra

“…In addition, many In-rich clusters were generated in the HI-InGaN well 19 . However, in this work, the interface between the In 0.45 Ga 0.55 N well and the In 0.13 Ga 0.87 N barrier for the In 0.45 Ga 0.55 N/In 0.13 Ga 0.87 N QWs is relatively more distinct and higher quality than those of the previous results 20 , 21 . The improvement of interface quality between the In 0.45 Ga 0.55 N well and the In 0.13 Ga 0.87 N barrier for the RLED, preparared by the Ga-FI technique, is related to the increase in possiblity for In adatoms to migrate toward their optimal positions.…”

Realization of high-luminous-efficiency InGaN light-emitting diodes in the “green gap” range

“…The luminous efficiency of 19.58 lm/W achieved in this work is a very high value for c-plane InGaN-based LEDs with normal voltage, compared with previous work on yellow-green LEDs 29 . Our experimental data suggest that the hybrid MQW structure can effectively push the efficient InGaN LED emission toward longer wavelengths, connecting to the lower limit of the AlGaInP LEDs’ spectral range, thus enabling completion of the LED product line covering the entire visible spectrum with sufficient luminous efficacy, which is critical to the expansion of the solid state lighting market.…”

Enhancement of efficiency of InGaN-based light emitting diodes through strain and piezoelectric field management

“…[16][17][18][19] However, the output powers at high injection current of these devices currently do not outperform the best devices grown on (0001) planes (c-planes). 2,14,20,21 …”