InGaN RGB Light-emitting Diodes with Monolithically Integrated Photodetectors for Stabilizing Color Chromaticity

Abstract

A solution towards realizing color chromaticity stabilized InGaN RGB light-emitting diode (LED) is proposed and demonstrated. The InGaN/GaN MQWs play a key role in light emission from the LEDs and photodetection from the photodetectors (PDs). The spectral overlaps between the emission and absorption spectra are measured and the photocurrents of the PDs exhibit linear behavior with increasing LED driving currents. The solution involves the use of RGB chips with monolithically-integrated PDs that detect the levels of light output from an individual chip in real-time, whose photocurrent signals are fed to LED driver circuits that make use of the signal to provide a driving current that stabilizes the light output. Adoption of this feedback strategy results in CIE coordinates drifts of $Delta$ (0.003, 0.005) over the 400-hr duration of testing, proving to be an effective way of stabilizing color chromaticity from RGB LEDs.