Temperature dependence of electroluminescence intensity of green and blue InGaN single-quantum-well light-emitting diodes

Abstract

Temperature dependence of electroluminescence (EL) spectral intensity of the super-bright green and blue InGaN single-quantum-well (SQW) light-emitting diodes has been studied over a wide temperature range (T=15–300 K) under a weak injection current of 0.1 mA. It is found that when T is slightly decreased to 140 K, the EL intensity efficiently increases, as usually seen due to the improved quantum efficiency. However, with further decrease of T down to 15 K, it drastically decreases due to reduced carrier capture by SQW and trapping by nonradiative recombination centers. This unusual temperature-dependent evolution of the EL intensity shows a striking difference between green and blue SQW diodes owing to the different potential depths of the InGaN well. The importance of efficient carrier capture processes by localized tail states within the SQW is thus pointed out for enhancement of radiative recombination of injected carriers in the presence of the high-density dislocations.

Thermally activated carrier transfer processes in InGaN∕GaN multi-quantum-well light-emitting devices

“…The weaker but higher-energy peak was then attributed to the corresponding transition predicted for a random alloy of InGaN matrix. Hori et al 5,6 studied the temperature-dependent EL spectra in efficient blue and green LEDs produced also by Nichia, showing general features very similar to our observation. They had attributed the higher-energy peak possibly to GaN, although a large redshift was noticed compared with the band gap of GaN.…”

Interplay of external and internal field effects on radiative recombination efficiency in InGaN quantum well diodes

“…Previously quantum confinement effects in the InGaN quantum well and efficient carrier capturing by localized radiative recombination centers in quantum-dot-like states [3][4][5][6] have been claimed to be important for the high emission efficiency. Our previous studies of the temperature-dependent electroluminescence (EL) intensity in single-QW (SQW) diodes [8] show that efficient capture processes of injected carriers by localized tail states play an important role between 180 and 300 K. However, for temperatures below 100 K, an anomalous quenching of the EL intensity is observed, which we attribute to reduced carrier capture rates.…”

Overshoot effects of electron on efficiency droop in InGaN/GaN MQW light-emitting diodes

“…24 Recently, an anomalous temperature-dependence of electroluminescence intensity in GaN-based LEDs was reported. [27][28][29][30] It was found that when temperature is decreased to around 200 K, the EL intensity rises, as expected from the improved quantum efficiency. However with a further decrease in temperature, the EL intensity falls dramatically.…”

“…However with a further decrease in temperature, the EL intensity falls dramatically. That phenomenon was explained by reduced carrier capture by QWs at low temperature, [27][28][29] or by the low ionization rate of magnesium (Mg) in p-GaN at low temperature. 30 In our simulation, Fig.…”