Degradation analysis with characteristics and simulations of 265 nm UV-C LED

Zhu, Xinglin; Su, Mengwei; Chen, Zhiqiang; Deng, Shaodong; Yao, Huilu; Wang, Yukun; Chen, Ziqian; Deng, Jixian; Sun, Wenhong

doi:10.1007/s10854-021-06113-z

Cited by 9 publications

(6 citation statements)

References 38 publications

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“…In the past two decades, researchers have made a great deal of efforts to improve the EQE and WPE of AlGaN‐based UV LEDs, which have made great progress. [ 5–7,11,17–19,30,33–91 ] Figures and show the EQE and WPE for UV LEDs of different emission wavelengths by various research groups (till dated 2021/8/30) respectively. As shown in Figure 2, we can see that the EQE gradually decreased while the emission wavelength reduced from 400 to 200 nm.…”

Section: Overview Of Algan‐based Uv Ledsmentioning

confidence: 99%

“…External quantum efficiency (EQE) of different peak wavelengths by various research groups. [ 5–7,11,17–19,30,33–91 ] The corresponding full name of mentioned abbreviations are listed as following: Chinese Academy of Sciences (CAS), Ferdinand‐Braun‐Institut, Berlin (FBH‐Berlin), Hebei University of Technology (HEBUT), Huazhong University of Science and Technology (HUST), Fraunhofer Institute for Applied Solid State Physics (IAF), National Chiao Tung University (NCTU), Nippon Telegraph and Telephone Corporation (NTT), National Institute of Information and Communications Technology (NICT), Ohio State University (OSU), Palo Alto Research Center (PARC), Sensor Electronic Technology, Inc (SETi), Technische Universität Berlin (TU Berlin), University of Wisconsin–Madison (UM‐Madison), University of South Carolina (USC), University of Science and Technology of China (USTC).…”

Section: Overview Of Algan‐based Uv Ledsmentioning

confidence: 99%

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Recent Advances in Packaging Technologies of AlGaN‐Based Deep Ultraviolet Light‐Emitting Diodes

Liang

Sun

2022

Adv Materials Technologies

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AlGaN‐based deep ultraviolet light‐emitting diodes (UV LEDs) have gained rapidly growing attention due to their wide applications in water purification, air disinfection, and sensing as well as optical communication. Moreover, deep UV radiation has been verified as one of effective way to inactivate COVID‐19. However, although numerous efforts have been made in deep UV LED chips, the reported highest external quantum efficiency (EQE) of them is 20.3%, which is far lower than that of visible LEDs. The EQE of commercial packaged AlGaN‐based deep UV LEDs is usually lower than 5%, which will cause serious reliability problems as well. Therefore, it is very urgent to improve EQE and reliability of the devices from packaging level. In this review, a systematical summarization about the packaging technologies of AlGaN‐based deep UV LEDs has been analyzed and future prospects have been made as well. Firstly, this work provides a brief overview of the devices and analyzes why the packaging level reduces EQE and reliability in theory. Then, systematically reviews the recent advances in packaging technologies and deep UV micro‐LEDs. Finally, conclusions and outlooks are given as well. This review is of great significance for promoting the development of the packaging technologies for AlGaN‐based deep UV LEDs.

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Section: Overview Of Algan‐based Uv Ledsmentioning

confidence: 99%

Section: Overview Of Algan‐based Uv Ledsmentioning

confidence: 99%

Recent Advances in Packaging Technologies of AlGaN‐Based Deep Ultraviolet Light‐Emitting Diodes

Liang

Sun

2022

Adv Materials Technologies

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“…It is worth bearing in mind that the same supposition was used as an estimation in the extraction of the clear depths and carrier concentration. The SCR often expands on both sides because the p-side contains limited charge concentration [ 72 ].…”

Section: Degradation Effects On C–v Characteristicsmentioning

confidence: 99%

“…In another study, our group carried out the C-V calculations at 1 MHz to observe the device aging [ 72 ]. In the forward-bias range (0–5) V, we observed the lowering of capacitance with the rise of the aging current.…”

Section: Degradation Effects On C–v Characteristicsmentioning

confidence: 99%

“…In another effort, our group noticed a rise of reverse leakage current and low forward bias region of the electrical stressed devices as shown in Figure 26 [ 72 ]. The rise of the reverse-bias leakage current throughout the procedure could be attributed to the increase in defect density about the active region.…”

Section: Degradation Effects On I–v Characteristicsmentioning

confidence: 99%

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Reliability Analysis of AlGaN-Based Deep UV-LEDs

2022

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The current pandemic crisis caused by SARS-CoV-2 has also pushed researchers to work on LEDs, especially in the range of 220–240 nm, for the purpose of disinfecting the environment, but the efficiency of such deep UV-LEDs is highly demanding for mass adoption. Over the last two decades, several research groups have worked out that the optical power of GaN-based LEDs significantly decreases during operation, and with the passage of time, many mechanisms responsible for the degradation of such devices start playing their roles. Only a few attempts, to explore the reliability of these LEDs, have been presented so far which provide very little information on the output power degradation of these LEDs with the passage of time. Therefore, the aim of this review is to summarize the degradation factors of AlGaN-based near UV-LEDs emitting in the range of 200–350 nm by means of combined optical and electrical characterization so that work groups may have an idea of the issues raised to date and to achieve a wavelength range needed for disinfecting the environment from SARS-CoV-2. The performance of devices submitted to different stress conditions has been reviewed for the reliability of AlGaN-based UV-LEDs based on the work of different research groups so far, according to our knowledge. In particular, we review: (1) fabrication strategies to improve the efficiency of UV-LEDs; (2) the intensity of variation under constant current stress for different durations; (3) creation of the defects that cause the degradation of LED performance; (4) effect of degradation on C-V characteristics of such LEDs; (5) I-V behavior variation under stress; (6) different structural schemes to enhance the reliability of LEDs; (7) reliability of LEDs ranging from 220–240 nm; and (8) degradation measurement strategies. Finally, concluding remarks for future research to enhance the reliability of near UV-LEDs is presented. This draft presents a comprehensive review for industry and academic research on the physical properties of an AlGaN near UV-LEDs that are affected by aging to help LED manufacturers and end users to construct and utilize such LEDs effectively and provide the community a better life standard.

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Variable temperature thermal droop characteristics of 255 nm UV LED

Deng

Chen

Min

et al. 2022

Applied Physics Letters

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Thermal droop, i.e., the loss of emission efficiency over a certain temperature range, is an important performance bottleneck for the successful commercial application of deep-ultraviolet light emitting diodes. In this study, we examined the mechanism of two thermal droop processes of 255 nm AlGaN quantum well light emitting diodes under temperature stresses in order to obtain steady optical output in a broad temperature range. We discovered that the increase in leakage current in the low forward bias region is accompanied by a decrease in apparent carrier concentration of quantum wells near the p side during the thermal droop process at high temperature (>300 K), indicating that the activation of thermal defects enhances the trap assisted tunneling effect and causes the optical power to decrease more significantly at low current. Compared with normal temperature, the low emission power at low temperatures is attributed to the minority trap H1, which has an activation energy of 0.527 eV at 190 K, according to deep level transient spectrum analysis. At low temperatures above 175 K, the optical power increases as the temperature rises due to enhanced hole injection. By analyzing the droop characteristics, we concluded that the activation of thermal defects is the most probable cause of high temperature thermal droop in 255 nm AlGaN quantum well light emitting diodes, whereas hole trap H1, which is linked to gallium vacancy complexes related defects, is most likely the source of low temperature thermal droop.

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Degradation analysis with characteristics and simulations of 265 nm UV-C LED

Cited by 9 publications

References 38 publications

Recent Advances in Packaging Technologies of AlGaN‐Based Deep Ultraviolet Light‐Emitting Diodes

Recent Advances in Packaging Technologies of AlGaN‐Based Deep Ultraviolet Light‐Emitting Diodes

Reliability Analysis of AlGaN-Based Deep UV-LEDs

Variable temperature thermal droop characteristics of 255 nm UV LED

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