Spatial inhomogeneity investigation of QW emission in InGaN MQW LEDs

Xia, Ruidong; Harrison, I.; Larkins, E.C.; Andrianov, A. V.; Dods, S.R.A.; Morgan, J.; Parbrook, P. J.; Button, Chris; Hill, G.

doi:10.1016/s0921-5107(02)00023-5

Cited by 6 publications

(5 citation statements)

References 10 publications

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“…These low-scale inhomogeneities in spatial EL distribution are related to the thermal degradation of InGaN QW 27) and propagating dislocation in LED's active region and p-side. 28,29) The EL observation for the pixel with applied hydrogen passivation, as shown in Fig. 3(b), has a dimmed frame around the pixel perimeter.…”

mentioning

confidence: 99%

InGaN-based green micro-LED efficiency enhancement by hydrogen passivation of the p-GaN sidewall

Kirilenko¹,

Iida²,

Zhuang³

et al. 2022

Appl. Phys. Express

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We investigated the effect of the sidewall passivation by hydrogen plasma on the InGaN green micro-LED performance. Hydrogen passivation deactivates the surface region of p-GaN around the perimeter of the device mesa. Thus, hole injection is suppressed in this region, where etching-caused material degradation results in leakage current, decreasing device efficiency. We have confirmed the hydrogen passivation effect on LED square pixels with sizes of 20 µm and 100 µm. For smaller LEDs, the reverse leakage current has reduced more than tenfold, and the external quantum efficiency of LEDs was enhanced 1.4-times due to the suppression of the non-radiative recombination.

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confidence: 99%

InGaN-based green micro-LED efficiency enhancement by hydrogen passivation of the p-GaN sidewall

Kirilenko¹,

Iida²,

Zhuang³

et al. 2022

Appl. Phys. Express

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“…15) These results suggest that the In content fluctuations contribute to the formation of the 570 and 600 nm peaks, which plays a key role in the white emission processes of InGaN MQWs. 16) Figure 8 shows the I-V characteristics of the 200m-diameter InGaN/GaN MQWs SAG-LED grown by MOCVD. The turn-on voltage of the InGaN/GaN MQWs SAG-LED is about 4.0 V. The values of the series resistance and leakage current are 5:0 Â 10 4 and 1.15 A, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…15) These results suggest that the In content fluctuations contribute to the formation of the 570 and 600 nm peaks, which plays a key role in the white emission processes of InGaN MQWs. 16) Figure 8 shows facets of the 200-m-diameter sample. The In composition of the 570-600 nm peak is estimated to be 0.45-0.51.…”

Section: Experimental Methodsmentioning

confidence: 99%

Characterization of the InGaN/GaN Multi-Quantum-Wells Light-Emitting Diode Grown on Patterned Sapphire Substrate with Wide Electroluminescence Spectrum

Lee

Jeon

Lee

et al. 2011

Jpn. J. Appl. Phys.

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We report the characterization of the InGaN/GaN multi-quantum-well (MQW) light-emitting diode (LED) grown on a patterned sapphire substrate by metal organic chemical vapor deposition (MOCVD) using the selective area growth (SAG) method. The SAG patterns were designed to be circular and their diameters were 700 and 200 m. After the growth, the InGaN/GaN MQW LED of 200 m diameter had various crystal facets and a shape similar to volcanic craters, which were not observed in the 700-m-diameter sample. We obtained an active layer with compositional nonuniformity and superior optical properties. We found wide electroluminescence (EL) spectral peaks near 470, 570, and 600 nm. The distribution of the EL spectrum of the sample was similar to that of a conventional phosphor-converted white LED.

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“…With SNOM, the low temperature and room temperature optical properties of InGaN/GaN QW were studied [9,10,11]. Especially, recently, with SNOM and micro-spectroscopy method, the electroluminescence property of GaN/InGaN QW was studied [12,13]. It was found that the distribution of Indium in InGaN induced the redistribution of carriers.…”

Section: Introductionmentioning

confidence: 99%

High spatial resolution investigation of electroluminescence of InGaN/GaN multiple quantum wells by using scanning near-field optical microscopy and spectroscopy

2005

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The electro-luminescence (EL) properties of InGaN/GaN multiple quantum wells (MQWs) light emitting diodes (LEDs) with various emitting wavelength (purple, blue and green) were studied by scanning near-field optical microscope (SNOM). The high spatial resolution EL SNOM mappings and near-field spectra of the LEDs were acquired at various injection current conditions. The experiment shows that, though there are some common points, the EL properties of various LEDs are quite different. (i) The EL mappings show that the MQWs emission is spatially inhomogenous, which contain many islands like bright spots. (ii) The sizes of the bright spots are different ranging from 0.1 µ m to 1µm, the LED with longer emitting wavelength has larger bright spots. (iii) The injection current dependences of the shape of the bright spots of various LEDs are different. (iv) The emission wavelengths of brighter spots are longer in the same LED. (v)Increasing the injection current, the full widths at half maximum (FWHM) of the EL spectra grow larger. With the same injection current, the green LED has larger FWHMs than the blue and purple ones. (vi) Increasing the injection current, the blue shift of the green LED is obviously (~60 meV), but those of the blue one and purple are negligible. The phenomena above suggest that, the self-organized In-rich regions play a key role in the emission of all the InGaN/GaN MQWs LEDs, though they have different influences on the emission properties of the three LEDs with various emission wavelengths.One possible explanation is that, in the blue and purple LEDs, because the size of the In-rich areas are small, the quantum confined Stark effect caused by the piezoelectric field is negligible; but in the green LED, the In-rich areas are larger, the quantum confined Stark effect is obvious which caused the blue shift phenomenon. And in all LEDs, the band filling effect makes the FWHMs of the emission spectra larger. The results also show that SNOM is a powerful tool to study the local light emission properties at n anometer scale.

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Spatial inhomogeneity investigation of QW emission in InGaN MQW LEDs

Cited by 6 publications

References 10 publications

InGaN-based green micro-LED efficiency enhancement by hydrogen passivation of the p-GaN sidewall

InGaN-based green micro-LED efficiency enhancement by hydrogen passivation of the p-GaN sidewall

Characterization of the InGaN/GaN Multi-Quantum-Wells Light-Emitting Diode Grown on Patterned Sapphire Substrate with Wide Electroluminescence Spectrum

High spatial resolution investigation of electroluminescence of InGaN/GaN multiple quantum wells by using scanning near-field optical microscopy and spectroscopy

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