Study on Optical Properties and Internal Quantum Efficiency Measurement of GaN-based Green LEDs

Lu, Boyang; Wang, Lai; Hao, Zhibiao; Luo, Yi; Sun, Changzheng; Han, Yongqin; Xiong, Bing; Wang, Jian; Li, Hongtao; Chen, Kaixuan; Xiang-Jing, Zhuo; Li, Jinchai; Kang, Junyong

doi:10.3390/app9030383

Cited by 11 publications

(8 citation statements)

References 24 publications

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“…In the 296 K mapping, the maximum intensity is located in the middle of the pixel and decreases while approaching the edges. When the temperature is lowered, the emitted intensity becomes higher, as expected from the suppression of non-radiative recombinations in the bulk and the surface [14], [15]. This increased emission of light at the edges of the MESA gives the impression that the MESA size is increasing while lowering temperature (in figure 2, the emission can be compared with the white dashed square which represents the emitted light at 296 K).…”

Section: Resultsmentioning

confidence: 90%

“…We conducted the CL characterization on another 6×6 µm² pixel in order to check the repeatability (Figure 8). Since the CL intensity I(T) is maximum at 30 K, we calculated a map representing the emission efficiency using the ratio [14] I(296 K)/I (30 K). This calculation was carried out after an alignment of the images realized at 296 K and 30 K (Figure 8c).…”

Section: Figure 7 Integrated CL Intensity Mappings At Different Temperatures For 36×36 µM² and 56×56 µM² Pixelsmentioning

confidence: 99%

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Investigation of sidewall damage induced by reactive ion etching on AlGaInP MESA for micro-LED application

Boussadi

Rochat

Barnes

et al. 2021

Journal of Luminescence

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Previous reports have studied the impact of sidewall defects on AlGaInP micro light emitting diode (µLED) only by Current-Voltage-Luminescence (I-V-L) measurements. In this work, we propose an alternative approach to investigate these defects directly after MESA formation, by coupling optical characterization techniques together with Time-of-flight secondary ion mass spectrometry (TOF-SIMS) on AlGaInP square shaped pixels of different sizes formed by BCl3-based Reactive Ion Etching (RIE). It is found that for a 6×6 µm² pixel, the light emission homogeneity is largely impacted by the sidewall defects. From emission efficiency map deduced by temperature-dependent cathodoluminescence measurements, we estimate that 86% of the 6×6 µm² pixel exhibit a lower efficiency than the center. The carriers lifetime extracted from time-resolved photoluminescence (TRPL) measurements on larger pixel begins to decrease gradually at 3 µm from the sidewall due to non-radiative recombinations. On the other hand, the TOF-SIMS analysis shows that residues of boron and chlorine remain on the surface and sidewalls of the pixel after BCl3 etching. These results show the importance to characterize the µLEDs at the MESA step and the necessity to optimize the etching process and the passivation.

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Section: Resultsmentioning

confidence: 90%

Section: Figure 7 Integrated CL Intensity Mappings At Different Temperatures For 36×36 µM² and 56×56 µM² Pixelsmentioning

confidence: 99%

Investigation of sidewall damage induced by reactive ion etching on AlGaInP MESA for micro-LED application

Boussadi

Rochat

Barnes

et al. 2021

Journal of Luminescence

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show abstract

“…The strength of electron–phonon interaction can be described by Huang–Rhys factor, [ 19 ] which can be approximated by the intensity ratio of first‐order phonon replica to zero‐phonon line at low temperature. [ 20 ] The value for GaN‐based materials obtained from experimental data [ 21 ] is ≈10 −1 –10 −2 , implying that vibronic coupling is considerably weak. It can be inferred that multiphoton process whose probability is smaller than observed EQE by several orders of magnitude is rather rare to occur and cannot sustain appreciable emission.…”

Section: Scientific Challenges and Possible Solutionsmentioning

confidence: 99%

Dennard Scaling in Optoelectronics: Scientific Challenges and Countermeasures of Micro‐LEDs for Displays

Wang

Hao

et al. 2022

Laser & Photonics Reviews

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Scaling‐down is the most significant technical strategy to improve performance for microelectronic devices, which is first performed systematically by Robert H. Dennard for silicon integrated circuits. Its main idea is that device parameters such as doping and junction depth must be adjusted when shrinking the dimensions of a field‐effect transistor so that the power density can remain unchanged. Recently, miniaturization of light‐emitting diodes or “microscale light‐emitting diodes (Micro‐LEDs)” is gaining much attention because of their potential for superior display technologies. However, the scaling‐down of LEDs used for solid‐state lighting (SSL) results in extremely low efficiency devices, with the reasons and underlying device physics still unclear. Here the law of Micro‐LED scaling is proposed in analogy to Dennard scaling, through which new perspectives are provided to comprehensively understand the root cause of Micro‐LED inefficiency and the scientific challenges to be addressed for mass commercialization, including subthreshold radiation, size‐dependent effect, and the enhancement of carrier recombination at low current density.

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“…The light source used in the PL experiment is a 405 nm solid-state laser, the output power of which is decreased to 1 mW to eliminate additional thermal effect, and the spot measures about 55 μm in radius. 23) Figure 1 shows the PL intensity, V OC , and I SC of the two LED samples measured under different bias and temperature conditions. Even though the shapes of these data points are different, it can be observed that the PL intensity and V OC under OC conditions have a similar trend with temperature, while the PL intensity and I SC under SC conditions change contrariwise with temperature, namely the decrease of PL intensity is accompanied by the increase of I SC .…”

mentioning

confidence: 99%

The correlation between carrier escape and injection in InGaN/GaN light-emitting diodes

Lu¹,

Hao²,

Luo³

et al. 2022

Appl. Phys. Express

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The processes of carrier escape and injection in InGaN/GaN light-emitting diodes (LEDs) have been studied separately and the underlying correlation between these two processes has been overlooked for long. In this study, the behavior of photogenerated carriers in LEDs is discussed which shows that the process of carrier escape and injection share the same transport channel. It is further confirmed through comparing the forward voltage under electrical-excitation and open-circuit voltage under photo-excitation with same luminous intensity. These results will not only deepen our understanding of device physics, but also guide the design of devices using for display and detection.

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Study on Optical Properties and Internal Quantum Efficiency Measurement of GaN-based Green LEDs

Cited by 11 publications

References 24 publications

Investigation of sidewall damage induced by reactive ion etching on AlGaInP MESA for micro-LED application

Investigation of sidewall damage induced by reactive ion etching on AlGaInP MESA for micro-LED application

Dennard Scaling in Optoelectronics: Scientific Challenges and Countermeasures of Micro‐LEDs for Displays

The correlation between carrier escape and injection in InGaN/GaN light-emitting diodes

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