Optical power degradation mechanisms in 271 nm AlGaN-based deep ultraviolet light-emitting diodes

Shen, C.F.; Yang, Renlong; Gong, Honglin; Zhu, Lihong; Gao, Yue; Chen, Guolong; Chen, Zhong; Lu, Yijun

doi:10.1364/oe.486393

Cited by 4 publications

(6 citation statements)

References 33 publications

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“…During the 1000 h aging test, the LOP of UVC LEDs packaged with the 3D PhC reflector and Au plating decreased by 7% and 8%, respectively, as shown in Figure 5 . Various optical power degradation mechanisms have been observed in UVC LEDs at different stages of degradation, including hillock-related and stress-induced defects [ 24 , 25 ]. The results of the 1000 h aging test indicated that UVC LEDs containing 3D PhC samples were nearly consistent with commercial UVC LEDs, and the 3D PhCs deposited on the UVC LED lead frame remained undamaged, demonstrating excellent reliability.…”

Section: Resultsmentioning

confidence: 99%

Enhancement of Light Efficiency of Deep-Ultraviolet Light-Emitting Diodes by Encapsulation with a 3D Photonic Crystal Reflecting Layer

Lai,

Lin,

Lee

2024

Nanomaterials

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Recently, UVC LEDs, which emit deep ultraviolet light, have found extensive applications across various fields. This study demonstrates the design and implementation of thin films of three-dimensional photonic crystals (3D PhCs) as reflectors to enhance the light output power (LOP) of UVC LEDs. The 3D PhC reflectors were prepared using the self-assembly of silica nanospheres on a UVC LED lead frame substrate via the evaporation-induced method (side) and the gravitational sedimentation method (bottom), respectively. These PhCs with the (111) crystallographic plane were deposited on the side wall and bottom of the UVC LED lead frame, acting as functional materials to reflect UVC light. The LOP of UVC LEDs with 3D PhC reflectors at a driving current of 100 mA reached 19.6 mW. This represented a 30% enhancement compared to commercial UVC LEDs with Au-plated reflectors, due to the UVC light reflection by the photonic band gaps of 3D PhCs in the (111) crystallographic plane. Furthermore, after aging tests at 60 °C and 60% relative humidity for 1000 h, the relative LOP of UVC LEDs with 3D PhC reflectors decreased by 7%, which is better than that of commercial UVC LEDs. Thus, this study offers potential methods for enhancing the light output efficiency of commercial UVC light-emitting devices.

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Section: Resultsmentioning

confidence: 99%

Enhancement of Light Efficiency of Deep-Ultraviolet Light-Emitting Diodes by Encapsulation with a 3D Photonic Crystal Reflecting Layer

Lai,

Lin,

Lee

2024

Nanomaterials

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“…Still these interfaces include an intermediate layer of oxidized III-V or SiC, which might be useful to include in theoretical models to predict the properties of these interfaces. Recent studies have presented energetically favored structures for oxidized GaAs (100) and InP(100) surfaces [216,233], which provide a realistic platform to simulate the interface properties and their modifications.…”

Section: Which Interface Defects Do Cause Extra Electron Levels In Th...mentioning

confidence: 99%

“…The third critical factor is durability of the Ohmic contacts. For example, degradation of the Ohmic contact of p-GaN decreases operation time of ultraviolet LED [100].…”

Section: Trade-off Between Ohmic and Recombination Losses At Metal-se...mentioning

confidence: 99%

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Bridging the gap between surface physics and photonics

Laukkanen,

Punkkinen,

Kuzmin

et al. 2024

Rep. Prog. Phys.

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Use and performance criteria of photonic devices increase in various application areas such as information and communication, lighting, and photovoltaics. In many current and future photonic devices, surfaces of a semiconductor crystal are a weak part causing significant photo-electric losses and malfunctions in applications. These surface challenges, many of which arise from material defects at semiconductor surfaces, include signal attenuation in waveguides, light absorption in light emitting diodes, non-radiative recombination of carriers in solar cells, leakage (dark) current of photodiodes, and light reflection at solar cell interfaces for instance. To reduce harmful surface effects, the optical and electrical passivation of devices has been developed for several decades, especially with the methods of semiconductor technology. Because atomic scale control and knowledge of surface-related phenomena have become relevant to increase the performance of different devices, it might be useful to enhance the bridging of surface physics to photonics. Toward that target, we review some evolving research subjects with open questions and possible solutions, which hopefully provide example connecting points between photonic device passivation and surface physics. One question is related to the properties of the wet chemically cleaned semiconductor surfaces which are typically utilized in device manufacturing processes, but which appear to be different from crystalline surfaces studied in ultrahigh vacuum by physicists. In devices, a defective semiconductor surface often lies at an embedded interface formed by a thin metal or insulator film grown on the semiconductor crystal, which makes the measurements of its atomic and electronic structures difficult. To understand these interface properties, it is essential to combine quantum mechanical simulation methods. This review also covers metal-semiconductor interfaces which are included in most photonic devices to transmit electric carriers to the semiconductor structure. Low-resistive and passivated contacts with an ultrathin tunnelling barrier are an emergent solution to control electrical losses in photonic devices.

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“…The first mechanism is associated with the complete lack of emission of optical radiation, while the second is associated with its successive loss and from the operational point of view is a significant problem because, despite the actual operation of the system, it leads to a deterioration in the effectiveness of the disinfection process [22]. The gradual degradation of the OP of LED depends on the operating temperature and current density [22,[28][29][30][31][32] and is the fastest during the first 10-200 h of operation, then the process slows down [19,21,[33][34][35][36][37]. According to [22,38], the UVC LED's lifetime is inversely proportional to the third power of the stress current density.…”

Section: Introductionmentioning

confidence: 99%

Degradation- and Thermal-Related Changes in Selected Electro-Optical Parameters of High-Power 270–280 nm LEDs

Gryko,

Błaszczak,

Kochanowicz

2023

Photonics

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Recently, the rapid development of LED sources emitting high-power radiation in the UVC range has been observed, and there is a growing interest in using these LED sources in practical solutions. The innovative constructions of disinfection and sterilization devices depend on the effectiveness and reliability of UVC radiation sources. At the same time, the literature reports that deep experimental analysis of degradation of high-power LEDs is limited. The aim of this research is to contribute to existing knowledge through a comparative assessment of the changes in optical power, spectral power distribution, and forward voltage drop in time and temperature of exemplary high-power UVC LEDs. For this purpose, a controlled 1500 h degradation of six different high-power UVC LEDs was performed, based on which we determined their expected lifetimes L70, L80, and L90. According to our results, the L80 varies from 180 h to 1500 h. Stronger degradation of optical power was observed with lower current. No significant impact on the spectral parameters was observed. The results also indicate the low influence of temperature on the voltage (<0.12%/°C), optical power (<0.22%/°C), and spectral parameters (peak wavelength Δλ and full width at half maximum ΔFWHM < 0.025 nm/°C).

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Optical power degradation mechanisms in 271 nm AlGaN-based deep ultraviolet light-emitting diodes

Cited by 4 publications

References 33 publications

Enhancement of Light Efficiency of Deep-Ultraviolet Light-Emitting Diodes by Encapsulation with a 3D Photonic Crystal Reflecting Layer

Enhancement of Light Efficiency of Deep-Ultraviolet Light-Emitting Diodes by Encapsulation with a 3D Photonic Crystal Reflecting Layer

Bridging the gap between surface physics and photonics

Degradation- and Thermal-Related Changes in Selected Electro-Optical Parameters of High-Power 270–280 nm LEDs

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