Enhanced Light Output of Near-Ultraviolet LEDs With Ta2O5/SiO2 Hybrid DBR Reflector

Ma, Yanfei; Fan, Bingfeng; Chen, Zimin; Lao, Yuqin; Yan, Linchao; Ma, Xiang; Zhuo, Yi; Pei, Yanli; Wang, Gang

doi:10.1109/lpt.2017.2737029

Cited by 7 publications

(5 citation statements)

References 12 publications

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“…DBRs have been used as high reflective mirrors in many UV-based photonic devices (summarized in Table 5), e.g., vertical-cavity surface-emitting laser (VCSEL), [129][130][131] edge-emitting laser (EEL), 139 microdisk LD, 137 resonant-cavity LED (RCLED), 132 resonant-cavity PD (RCPD), 133 and LEDs. 70,[134][135][136]138 These DBRs were formed using oxides named as UV-dielectric DBR and group III-nitride semiconductors, named as UV-nitride DBR. Most of the aforementioned UVbased photonic devices require DBR(s) with high reflectivity, R > 99%.…”

Section: -D Photonic Crystals: Distributed Bragg Reflectormentioning

confidence: 99%

“…Despite the advantages of the UV-dielectric DBRs, e.g., extensive material choices, fabrication flexibility, highly reflective, high RI contrast, and the wide stopband, the major drawback is that they are not electrically conductive and the thermal conductivity is mostly low. A complex current injection device scheme, e.g., intracavity 132,134 or flip-chip, 138 is required to pump a LEDs with dielectric DBRs electrically. Moreover, the poor thermal conductivity of dielectric DBRs deters the dissipation of heat generated during lasing operation.…”

Section: -D Photonic Crystals: Distributed Bragg Reflectormentioning

confidence: 99%

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Review of nanophotonics approaches using nanostructures and nanofabrication for III-nitrides ultraviolet-photonic devices

et al. 2018

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Group III-nitride semiconductor materials especially AlGaN are key-emerging candidates for the advancement of ultraviolet (UV) photonic devices. Numerous nanophotonics approaches using nanostructures (e.g., nanowires, nanorods, and quantum dots/disks) and nanofabrication (e.g., substrate patterning, photonic crystals, nanogratings, and surface-plasmons) have been demonstrated to address the material growth challenges and to enhance the device efficiencies of photonic devices operating at UV wavelengths. Here, we review the progress of nanophotonics implementations using nanostructured interfaces and nanofabrication approaches for the group III-nitride semiconductors to realize efficient UV-based photonic devices. The existing challenges of nanophotonics applications are presented. This review aims to provide analysis of state-of-the-art nanophotonic approaches in advancing the UV-photonic devices based on group III-nitride semiconductors. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: -D Photonic Crystals: Distributed Bragg Reflectormentioning

confidence: 99%

Section: -D Photonic Crystals: Distributed Bragg Reflectormentioning

confidence: 99%

Review of nanophotonics approaches using nanostructures and nanofabrication for III-nitrides ultraviolet-photonic devices

et al. 2018

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“…As an alternative, dielectric DBRs have been extensively employed in FCLEDs owing to their superior reflectivity and remarkable mechanical robustness. Conventional single-DBR stack and double-DBR stacks suffer from a narrow reflectance bandwidth and strong angular dependence [27,28]. Recently, our groups have proposed wide reflected angle DBR (WRA-DBR) and quintuple-stack DBR to broad reflectance bandwidth and alleviate angular dependence [29,30].…”

Section: Introductionmentioning

confidence: 99%

Effect of distributed Bragg reflectors on optoelectronic characteristics of GaN-based flip-chip light-emitting diodes

Sun,

Shi,

Cui

et al. 2024

Semicond. Sci. Technol.

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Distributed Bragg reflectors have been widely utilized in GaN-based flip-chip light-emitting diodes (FCLEDs) owing to their excellent reflection performance. Recently, wide reflected angle DBR (WRA-DBR) has been suggested to enhance the optical characteristics of GaN-based FCLEDs by incorporating multiple sub-DBRs with varying central wavelengths. However, the reflectivity of WRA-DBR decreases at large incident angle from 425 nm to 550 nm, which restricts further optical performance improvement of FCLEDs. Here, we demonstrate a quintuple-stack DBR comprised of five sub-DBRs. The quintuple-stack DBR possesses a high reflectivity (>97.5%) for incident angles below 50° within the blue and green light wavelength ranges. Compared to WRA-DBR, quintuple-stack DBR exhibits a higher reflectivity in wavelength range of 425 nm to 550 nm and thinner multilayer thicknesses. Furthermore, stronger electric field intensities exist in the top facet and sidewalls of FCLED with quintuple-stack DBR, revealing that quintuple-stack DBR is beneficial for enhancing the light extraction efficiency. As a result, the light output power of FCLED with quintuple-stack DBR is ~3% higher than that of FCLED with WRA-DBR at 750 mA.

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“…Furthermore, the bandgap of Ta 2 O 5 is 4.1 eV, which is transparent to UV light and has potential applications in UV LEDs. 26,27) Here, comparative experimental and simulation studies of conventional top-emitting (TE) UV LEDs and high-performance FC-UV LEDs were carried out. The Ta 2 O 5 =SiO 2 DBR and SiO 2 current blocking layer (CBL) were used to fabricate high-performance FC-UV LEDs.…”

Section: Introductionmentioning

confidence: 99%

Comparative experimental and simulation studies of high-power AlGaN-based 353 nm ultraviolet flip-chip and top-emitting LEDs

Liu¹,

Zhou²,

Liu³

et al. 2018

Jpn. J. Appl. Phys.

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Experimental and simulation studies of high-power AlGaN-based 353 nm ultraviolet (UV) flip-chip (FC) and top-emitting (TE) light-emitting diodes (LEDs) are performed here. To improve the optical and electrical properties of ultraviolet LEDs, we fabricate high-power FC-UV LEDs with Ta 2 O 5 / SiO 2 distributed Bragg reflectors (DBRs) and a strip-shaped SiO 2 current blocking layer (CBL). The reflectance of fourteen pairs of Ta 2 O 5 /SiO 2 DBRs is 96.4% at 353 nm. The strip-shaped SiO 2 CBL underneath the strip-shaped p-electrode can prevent the current concentrating in regions immediately adjacent to the p-electrode where the overlying opaque p-electrode metal layer absorbs the emitted UV light. Moreover, two-level metallization electrodes are used to improve current spreading. Our numerical results show that FC-UV LED has a more favorable current spreading uniformity than TE-UV LED. The light output power of 353 nm FC-UV LED was 23.22 mW at 350 mA, which is 24.7% higher than that of TE-UV LED.

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Enhanced Light Output of Near-Ultraviolet LEDs With Ta₂O₅/SiO₂ Hybrid DBR Reflector

Cited by 7 publications

References 12 publications

Review of nanophotonics approaches using nanostructures and nanofabrication for III-nitrides ultraviolet-photonic devices

Review of nanophotonics approaches using nanostructures and nanofabrication for III-nitrides ultraviolet-photonic devices

Effect of distributed Bragg reflectors on optoelectronic characteristics of GaN-based flip-chip light-emitting diodes

Comparative experimental and simulation studies of high-power AlGaN-based 353 nm ultraviolet flip-chip and top-emitting LEDs

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