Structural and optical investigations of AlGaN MQWs grown on a relaxed AlGaN buffer on AlN templates for emission at 280nm

Li, X.; Gac, G; Bouchoule, S.; Gmili, Youssef El; Patriarche, G.; Disseix, P.; Réverêt, François; Leymarie, J.; Streque, Jérémy; Genty, F.; Salvestrini, Jean Paul; Dupuis, R. D.; Li, X. H.; Voss, Paul L.; Ougazzaden, A.

doi:10.1016/j.jcrysgro.2015.09.013

Cited by 9 publications

(6 citation statements)

References 30 publications

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“…The large pits we observe are similar to previously reported hexagonal V-pits that form in AlGaN grown on AlN templates on sapphire [ 11 ]. One model for V-pit formation is that growth is slowed by the segregation of impurities around a threading dislocation and the slower growth forms a pit.…”

Section: Discussionsupporting

confidence: 90%

Porous AlGaN-Based Ultraviolet Distributed Bragg Reflectors

2018

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Utilising dislocation-related vertical etching channels in gallium nitride, we have previously demonstrated a simple electrochemical etching (ECE) process that can create layered porous GaN structures to form distributed Bragg reflectors for visible light at wafer scale. Here, we apply the same ECE process to realise AlGaN-based ultraviolet distributed Bragg reflectors (DBRs). These are of interest because they could provide a pathway to non-absorbing UV reflectors to enhance the performance of UV LEDs, which currently have extremely low efficiency. We have demonstrated porous AlGaN-based UV DBRs with a peak reflectance of 89% at 324 nm. The uniformity of these devices is currently low, as the as-grown material has a high density of V-pits and these alter the etching process. However, our results indicate that if the material growth is optimised, the ECE process will be useful for the fabrication of UV reflectors.

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Section: Discussionsupporting

confidence: 90%

Porous AlGaN-Based Ultraviolet Distributed Bragg Reflectors

2018

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“…The peak emission wavelength of DUV LED was 270 nm. The FWHM of PL spectrum of the DUV LED was 14 nm, which is close to the reported FWHM value in previous work [50]. Figure 13e shows the current versus voltage characteristic of DUV LED.…”

Section: Resultssupporting

confidence: 88%

Heteroepitaxial Growth of High-Quality and Crack-Free AlN Film on Sapphire Substrate with Nanometer-Scale-Thick AlN Nucleation Layer for AlGaN-Based Deep Ultraviolet Light-Emitting Diodes

Zhao

Lei

et al. 2019

Nanomaterials

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High-quality and crack-free aluminum nitride (AlN) film on sapphire substrate is the foundation for high-efficiency aluminum gallium nitride (AlGaN)-based deep ultraviolet light-emitting diodes (DUV LEDs). We reported the growth of high-quality and crack-free AlN film on sapphire substrate with a nanometer-scale-thick AlN nucleation layer (NL). Three kinds of nanometer-scale-thick AlN NLs, including in situ low-temperature AlN (LT-AlN) NL, oxygen-undoped ex situ sputtered AlN NL, and oxygen-doped ex situ sputtered AlN NL, were prepared for epitaxial growth of AlN films on sapphire substrates. The influence of nanoscale AlN NL thickness on the optical transmittance, strain state, surface morphology, and threading dislocation (TD) density of the grown AlN film on sapphire substrate were carefully investigated. The average optical transmittance of AlN film on sapphire substrate with oxygen-doped sputtered AlN NL was higher than that of AlN films on sapphire substrates with LT-AlN NL and oxygen-undoped sputtered AlN NL in the 200–270 nm wavelength region. However, the AlN film on sapphire substrate with oxygen-undoped sputtered AlN NL had the lowest TD density among AlN films on sapphire substrates. The AlN film on sapphire substrate with the optimum thickness of sputtered AlN NL showed weak tensile stress, a crack-free surface, and low TD density. Furthermore, a 270-nm AlGaN-based DUV LED was grown on the high-quality and crack-free AlN film. We believe that our results offer a promising and practical route for obtaining high-quality and crack-free AlN film for DUV LED.

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“…First, the V-pits in their AlN layers clearly originate from open-core dislocations, and they are full inverted piramids with {1 0 −1 1} facets. 35 Our shallow pits, in contrast, present rather {1 0 −1 3} facets and are truncated inverted piramids, with the dislocation associated with one of the faceted steps. Second, in our case, areas with deformed QD layers tend to close along the growth axes, forming a cone, whereas the inverted piramids reported by Mogilatenko et al 28 have a tendency to spread.…”

Section: Resultsmentioning

confidence: 81%

“…An AFM image of the surface morphology of the sample is provided as Figure S1 in the Supporting Information. The “pits” are relatively shallow, with a typical width on the order of 100 nm and a depth around 10 nm, resulting in a larger width-to-depth aspect ratio compared to the characteristic V-pit defects in InGaN or AlGaN, which present {1 0 −1 1} facets. Instead, they have a similar size as trench defects but lack their characteristic contour of grooves …”

Section: Resultsmentioning

confidence: 99%

Effect of Extended Defects on AlGaN Quantum Dots for Electron-Pumped Ultraviolet Emitters

Cañas,

Rochat,

Grenier

et al. 2024

ACS Nano

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We study the origin of bimodal emission in AlGaN/AlN QD superlattices displaying a high internal quantum efficiency (around 50%) in the 230−300 nm spectral range. The secondary emission at longer wavelengths is linked to the presence of cone-like domains with deformed QD layers, which originate at the first AlN buffer/superlattice interface and propagate vertically. The cones originate at a 30°-faceted shallow pit in the AlN, which appears to be associated with a threading dislocation that produces strong shear strain. The cone-like structures present Ga enrichment at the boundaring facets and larger QDs within the conic domain. The bimodality of the luminescence is attributed to the differing dot size and composition within the cones and at the faceted boundaries, which is confirmed by the correlation of microscopy results and Schrodinger−Poisson calculations.

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Structural and optical investigations of AlGaN MQWs grown on a relaxed AlGaN buffer on AlN templates for emission at 280nm

Cited by 9 publications

References 30 publications

Porous AlGaN-Based Ultraviolet Distributed Bragg Reflectors

Porous AlGaN-Based Ultraviolet Distributed Bragg Reflectors

Heteroepitaxial Growth of High-Quality and Crack-Free AlN Film on Sapphire Substrate with Nanometer-Scale-Thick AlN Nucleation Layer for AlGaN-Based Deep Ultraviolet Light-Emitting Diodes

Effect of Extended Defects on AlGaN Quantum Dots for Electron-Pumped Ultraviolet Emitters

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