282-nm AlGaN-based deep ultraviolet light-emitting diodes with improved performance on nano-patterned sapphire substrates

Dong, Peng; Yan, Jianchang; Wang, Junxi; Zhang, Yun; Geng, Chong; Wei, Tongbo; Cong, Peipei; Zhang, Yiyun; Zeng, Jianping; Tian, Ye; Sun, Lili; Yan, Qingfeng; Li, Jinmin; Fan, Shunfei; Qin, Zhixin

doi:10.1063/1.4812237

Cited by 194 publications

(141 citation statements)

References 23 publications

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“…The type and density of the TDs were investigated by weak beam dark field TEM imaging. For detailed analysis of the dislocation movement within the crystal structure the sample was cut in the (10-10) and (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) zone axes. The samples were then tilted to a 2 beam condition in the g = (11-20) and g = (10-10) directions respectively, where only the edge and mixed (edge and screw) type dislocations were visible.…”

Section: Structural Characterisationsmentioning

confidence: 99%

“…17 However the fundamental problem with growing desirable highly dense arrays of III-N nanorods is their tendency to coalesce forming continuous layers. 18,19 The initial radial growth of nanorods is known to begin immediately after nucleation, 20 resulting in coalescence early on if the density of the rods is very high in growth both by MOCVD and molecular beam epitaxy.…”

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confidence: 99%

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Ultra-High-Density Arrays of Defect-Free AlN Nanorods: A “Space-Filling” Approach

Conroy

Zubialevich²,

Li³

et al. 2016

ACS Nano

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Section: Structural Characterisationsmentioning

confidence: 99%

mentioning

confidence: 99%

Ultra-High-Density Arrays of Defect-Free AlN Nanorods: A “Space-Filling” Approach

Conroy

Zubialevich²,

Li³

et al. 2016

ACS Nano

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“…As investigated by Kueller et al 18 , a smooth crack free overgrown AlN layer can only be formed when the stripes are orientated in the (1-100) direction. Whereas the (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) direction will give a strongly faceted surface, leading to inhomogeneous Al distribution in AlGaN layers grown subsequently in UV LED devices. The orientation requirements for this patterning demands a high level expertise in expensive lithography alignment and additional processing steps.…”

Section: Introductionmentioning

confidence: 99%

Epitaxial lateral overgrowth of AlN on self-assembled patterned nanorods

Conroy

Zubialevich

et al. 2015

J. Mater. Chem. C

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We report an inexpensive nanoscale patterning process for epitaxial lateral overgrowth (ELOG) in AlN layers grown by metal organic vapour phase epitaxy (MOVPE) on sapphire. The pattern was produced by an inductively coupled plasma etch using a self-assembled monolayer of silica spheres on AlN as the lithographic mask. The resulting uniform 1 [small mu ]m length rod structure across a wafer showed a massive reduction in threading dislocations (TDs) when annealed at 1100 [degree]C. Overgrowing homoepitaxial AlN on top of the nanorods, at a temperature of 1100 [degree]C, produced a crack free coalesced film with approximately 4 [small mu ]m of growth, which is formed at a much lower temperature compared to that typically required for microscale ELOG. The improved crystal quality, in terms of TD reduction, of the AlN above the rods was determined by detailed weak beam (WB) electron microscopy studies and showed that the threading dislocation density (TDD) was greatly reduced, by approximately two orders of magnitude in the case for edge-type dislocations. In situ reflectance measurements during the overgrowth allowed for thickness coalescence to be estimated along with wafer curvature changes. The in situ measurements also confirmed that tensile strain built up at a much slower rate in the ELOG AlN layer compared to that of AlN prepared directly on sapphire

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“…Reported external quantum efficiencies (EQE) for group III-nitrides-based near and deep UV LEDs. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] In part courtesy of Prof. M. Kneissl of Technische Universität Berlin.…”

Section: Current Status and Challenges Of Group Iii-nitrde Duv Ledsmentioning

confidence: 99%

Status of Growth of Group III-Nitride Heterostructures for Deep Ultraviolet Light-Emitting Diodes

Ding¹,

Avrutin²,

Özgür³

et al. 2017

Preprint

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Abstract:We overview recent progress in growth aspects of group III-nitride heterostructures for deep ultraviolet (DUV) light-emitting diodes (LEDs), with particular emphasis on the growth approaches for attaining high-quality AlN and high Al-molar fraction AlGaN. The discussion commences with the introduction of the current status of group III-nitride DUV LEDs and the remaining challenges. This segues into discussion of LED designs enabling high device performance followed by the review of advances in the methods for the growth of bulk single crystal AlN intended as a native substrate together with a discussion of its UV transparency. It should be stated, however, that due to the high-cost of bulk AlN substrates at the time of this writing, the growth of DUV LEDs on foreign substrates such as sapphire still dominates the field. On the deposition front, the heteroepitaxial growth approaches incorporate high-temperature metal organic chemical vapor deposition (MOCVD) and pulsed-flow growth, a variant of MOCVD, with the overarching goal of enhancing adatom surface mobility, and thus epitaxial lateral overgrowth which culminates in minimization the effect of lattice-and thermal-mismatches. This is followed by addressing the benefits of pseudomorphic growth of strained high Al-molar fraction AlGaN on AlN. Finally, methods utilized to enhance both p-and n-type conductivity of high Al-molar fraction AlGaN are reviewed.

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282-nm AlGaN-based deep ultraviolet light-emitting diodes with improved performance on nano-patterned sapphire substrates

Cited by 194 publications

References 23 publications

Ultra-High-Density Arrays of Defect-Free AlN Nanorods: A “Space-Filling” Approach

Ultra-High-Density Arrays of Defect-Free AlN Nanorods: A “Space-Filling” Approach

Epitaxial lateral overgrowth of AlN on self-assembled patterned nanorods

Status of Growth of Group III-Nitride Heterostructures for Deep Ultraviolet Light-Emitting Diodes

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