Enhanced photo/electroluminescence properties of Eu-doped GaN through optimization of the growth temperature and Eu related defect environment

Zhu, Wanxin; Mitchell, Brandon; Timmerman, Dolf; Uedono, Akira; Koizumi, Akira; Fujiwara, Yoshihiro

doi:10.1063/1.4950826

Cited by 25 publications

(18 citation statements)

References 20 publications

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“…The light is absorbed in GaN and, subsequently, nonradiative recombination of the generated carriers can excite the Eu 3+ ions. The effectiveness of this excitation mechanism is strongly dependent on the local crystal environment of the Eu 3+ ions, and is influenced by defects and strain 16 , 17 .…”

Section: Discussionmentioning

confidence: 99%

Enhanced light extraction efficiency of Eu-related emission from a nano-patterned GaN layer grown by MOCVD

Lesage

Timmerman

Inaba

et al. 2019

Sci Rep

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Eu-doped GaN is a promising material for the active layer in red light emitting diodes. Although the output power of LEDs based on GaN:Eu has been increasing by a combination of structural and growth optimizations, there is still a significant limitation resulting from a poor light extraction efficiency, typical for high refractive index materials. Here we studied nanostructuring of the top of the optical active layer by nano-cubes for enhancement of the light extraction efficiency, and its effect on the optical emission characteristics. By etching nano-cubes into the active layer, we observed an increase in directional light output power of Eu3+ ions of up to 60%, as well as a grating effect. Simultaneously, the absorption of excitation light into the optical active layer was improved, leading to a 12.8 times increase of output power per available Eu3+ ion.

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Section: Discussionmentioning

confidence: 99%

Enhanced light extraction efficiency of Eu-related emission from a nano-patterned GaN layer grown by MOCVD

Lesage

Timmerman

Inaba

et al. 2019

Sci Rep

Self Cite

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“…The LT-MLS LED had a significantly higher maximum output power of ~110 µW, compared to 48 µW from the 300nm bulk LED. [9] Again, since the total GaN:Eu layer thickness was a factor of three lower for the LT-MLS LED, this means that the output power per GaN:Eu layer thickness was 5.8 times higher. This promising result indicated that an even higher output power could be achieved by increasing the number of pairs in the LT-MLS LED, as long as the output power scaled with the number of pairs.…”

Section: Resultsmentioning

confidence: 97%

“…Recently, it was found that the use of a new Eu precursor (EuCp pm 2 ) with a lower growth temperature of 960 o C reduced the surface roughness of GaN:Eu samples, and led to an enhancement of the integrated emission intensity. However, the photoluminescence (PL) emission spectra was quite broad, which was attributed to significant variations in the local defect structure around certain Eu ions, which may inhibit their optical activity [9]. A delta doped multilayer structure (MLS) containing 40 pairs of alternating GaN/GaN:Eu was recently shown to significantly increase the emissivity of Eu 3+ ions [10].…”

Section: Introductionmentioning

confidence: 99%

High-Power Eu-Doped GaN Red LED Based on a Multilayer Structure Grown at Lower Temperatures by Organometallic Vapor Phase Epitaxy

et al. 2017

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A modification of the growth structure of Eu-doped GaN (GaN:Eu) from a monolayer to a multilayer structure (MLS) consisting of alternating GaN and GaN:Eu, was shown to enhance the emission properties. Similarly, lowering the growth temperature of the GaN:Eu to 960°C nearly doubled the photoluminescence emission intensity, and also enhanced device performance. Hence, to design a higher power GaN:Eu red LED, a multilayer structure consisting of 40 pairs of alternating GaN and GaN:Eu was grown at 960°C. This combination resulted in the fabrication of an LED with a maximum output power of 110 μW, which is 5.8 times more output power per GaN:Eu layer thickness as compared to the best previously reported device. Moreover, it was found that the MLS sample grown at 960°C maintained a high crystal quality with low surface roughness, which enabled an increase in the number of pairs from 40 pairs to 100 pairs. An MLS-LED consisting of 100 pairs of alternating GaN/GaN:Eu layers was successfully fabricated, and had a maximum output power of 375 μW with an external quantum efficiency of 4.6%. These are the highest values reported for this system.

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“…[20] The influence of growth temperature on the surface morphology and luminescence properties of Eu-doped GaN layers grown by organometallic vapor phase epitaxy was investigated by Zhu and coworkers. [21] Luminescence properties of defects in thin GaN layers (200µm) are investigated by Reshchikov and coworkers. [22] These defects are supposed to notably affect the electrical and optical properties of the host material and can seriously degrade the performance and reliability of devices.…”

Section: Additional Literature Of Thin Film Doped Ganmentioning

confidence: 99%

Closing the Yellow Gap with Eu- and Tb-Doped GaN: One Luminescent Host Resulting in Three Colours

Braun¹,

Mereacre²,

Chen³

et al. 2020

Preprint

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GaN is a key material when it comes to highly efficient warm white all-nitride phosphor converted light emitting diodes (pc-LED). Here we present the doping of bulk GaN with Europium and Terbium and the combination of both resulting in intriguing luminescence properties, pushing the role of GaN:Eu,Tb as a chief component in future light emitiing diodes. By this colour tuning we prove that one luminescent host can provide three colours (red, green, orange) and even the so called "yellow gap" could be closed with a III-nitride.<br>

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Enhanced photo/electroluminescence properties of Eu-doped GaN through optimization of the growth temperature and Eu related defect environment

Cited by 25 publications

References 20 publications

Enhanced light extraction efficiency of Eu-related emission from a nano-patterned GaN layer grown by MOCVD

Enhanced light extraction efficiency of Eu-related emission from a nano-patterned GaN layer grown by MOCVD

High-Power Eu-Doped GaN Red LED Based on a Multilayer Structure Grown at Lower Temperatures by Organometallic Vapor Phase Epitaxy

Closing the Yellow Gap with Eu- and Tb-Doped GaN: One Luminescent Host Resulting in Three Colours

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