Analysis of the physical processes responsible for the degradation of deep-ultraviolet light emitting diodes

Meneghini, Matteo; Barbisan, Diego; Rodighiero, L.; Meneghesso, G.; Zanoni, Enrico

doi:10.1063/1.3497082

Cited by 41 publications

(9 citation statements)

References 20 publications

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“…In previous studies, it has been suggested that the yellow luminescence enhancement at 2.4 eV was attributed to the generation of defects with relatively low formation energy at moderate temperature. A possible explanation for the enhancement is the easy diffusion of and an oxygen atom sitting in a neighboring nitrogen site, which can partly compensate the unintentional n-type doping of the active region [19,[24][25][26].…”

Section: Resultsmentioning

confidence: 99%

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

Zhu

Chen

et al. 2021

J Mater Sci: Mater Electron

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We report the degradation study on AlGaN-based 265 nm ultraviolet light emitting diodes (UV-LEDs) under a series of constant current stress. The failure mechanisms were investigated systematically by measuring the optical and electrical characteristics of the LEDs before and after aging. The variation of carrier concentration in the active region was analyzed by capacitance-voltage. Combining the extracted apparent charge distribution pro les with the simulation results of the devices before and after the stress, we found that the change of carrier concentration in the multiple quantum wells was related to the donor diffusion on the n-side. On the p-side, both the acceptor concentration of electron blocking layer (EBL) and the defects in p-GaN contact layer were also found to be under constant change. The reduction of the EBL doping concentration has contributed to an increase of the diode depletion width during the stress. The changes in the LEDs before and after stressing indicate a compensating effect occurred in the p-type EBL close to the quantum wells, which leads to the degradation of the optical power of the 265 nm UV-LEDs.

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Section: Resultsmentioning

confidence: 99%

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

Zhu

Chen

et al. 2021

J Mater Sci: Mater Electron

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“…Matteo Meneghini et al described that at lesser current levels, the optical power (OP) lowering was outstanding which suggested that excessive defects favored the degradation [ 62 ]. Their work indicated that the increase of the defectiveness in the active layer led to greater degradation by gradually lowering the radiative efficiency ( Figure 13 ).…”

Section: Degradation Due To Defect Creationmentioning

confidence: 99%

“…In order to obtain distinct and accurate information of fixing the free charge in the active layer of the heterostructure, the apparent charge distribution (ACD) profiles are generally use the capacitance–voltage (C-V) measurements [ 62 , 69 , 70 ]. From the capacitance–voltage (C-V) measurements, it is possible to bring out the broadness of the space-charge region (SCR) and the quantity of the charge that depends upon the voltage at the junction, so that the capacitance of the barrier can be modified by altering given voltage.…”

Section: Degradation Effects On C–v Characteristicsmentioning

confidence: 99%

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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“…The problems that arise during the aging of the devices could be noted from different characteristics in the devices: (i) a decrease in the optical power [54,60,[62][63][64], (ii) the increase in the sub turn-on and reverse leakage currents [62], (iii) changes in the drive voltage [57,62], (iv) changes in the spectral characteristics [60,65], and (v) catastrophic failures [66]. The problems have been a topic of study for research groups for quite some time, and their causes could be summarized as: (i) generation of defects inside the active region [54,60], (ii) decrease in the injection efficiency during the aging [54], (iii) migration of defects or atoms through the heterostructure [65], (iv) activation and/or compensation of doping materials [57], and (v) leakage current paths through defects [62].…”

Section: State-of-the-art Commercial Devices: Performance and Reliabilitymentioning

confidence: 99%

UV-Based Technologies for SARS-CoV2 Inactivation: Status and Perspectives

et al. 2021

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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiologic agent of COVID-19, which has affected the international healthcare systems since the beginning of 2020. Among sanitizing approaches, UV irradiation is a well-known technology often used in different environments to reduce the microbial contamination and the viral transmission. In particular, several works have demonstrated that UVC radiation is able to inactivate SARS-CoV-2 compromising its viral genome and virion integrity. With this work we review and analyze the current status of the pandemic and the state of the art of the UV technology. With traditional UVC discharge lamps having a serious environmental issue, due to their working principle based on mercury, a primary focus is shifted on the aluminum gallium nitride based deep-ultraviolet light emitting diodes. These devices are exploited for compact and environmentally friendly disinfection systems, but efficiency and reliability still play a limiting role into their mass market adoption and system efficacy. In this work we then analyze the latest reports on the effects of dose and wavelength on viral inactivation, thus providing two key pillars for the development of UVC based disinfection systems: the status of the technology and a quantitative evaluation of the dose required to achieve an effective coronavirus inactivation.

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Analysis of the physical processes responsible for the degradation of deep-ultraviolet light emitting diodes

Cited by 41 publications

References 20 publications

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

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

Reliability Analysis of AlGaN-Based Deep UV-LEDs

UV-Based Technologies for SARS-CoV2 Inactivation: Status and Perspectives

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