High quality AlGaN grown on ELO AlN/sapphire templates

Zeimer, U.; Kueller, V.; Knauer, A.; Mogilatenko, A.; Weyers, M.; Kneissl, Michael

doi:10.1016/j.jcrysgro.2013.04.041

Cited by 94 publications

(99 citation statements)

References 14 publications

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“…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)(12)(13)(14)(15)(16)(17)(18)(19)(20) and g = (10-10) directions respectively, where only the edge and mixed (edge and screw) type dislocations were visible.…”

Section: Methodsmentioning

confidence: 99%

“…The samples were then tilted to a 2 beam condition in the g = (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) and g = (10-10) directions respectively, where only the edge and mixed (edge and screw) type dislocations were visible. All samples were tilted in the (0002) direction to make only screw type dislocations visible for TDD determination.…”

Section: Methodsmentioning

confidence: 99%

“…The detailed crystallographic information of overgrown AlN layers on AlN nanorods was observed using TEM in WBDF conditions. Two cross sections were cut out of the 1100 °C grown sample to observe the edge, screw and mixed type dislocations in the (10-10) and the (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) zone axes. Figures 7 and 8 show a TEM foil that is in the (10-10) zone axis.…”

Section: (A) (B)mentioning

confidence: 99%

“…5,6 There have been several different approaches to ELOG patterning templates, with the micron-stripe template the most common 15,16 achieving significant reductions in the TDD, as highlighted by Imura et al 17 . 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.…”

Section: Introductionmentioning

confidence: 99%

“…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%

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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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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: (A) (B)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Epitaxial lateral overgrowth of AlN on self-assembled patterned nanorods

Conroy

Zubialevich

et al. 2015

J. Mater. Chem. C

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Nitride Semiconductors

Dadgar¹,

Weyers²

2019

Metalorganic Vapor Phase Epitaxy (MOVPE)

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Drive High Power UVC‐LED Wafer into Low‐Cost 4‐Inch Era: Effect of Strain Modulation

Liu

Yuan

Huang

et al. 2022

Adv Funct Materials

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Ultraviolet-C light-emitting diodes (UVC-LEDs) have great application in pathogen inactivation under various kinds of situations, especially in the fight against COVID-19. Unfortunately, its epitaxial wafers are so far limited to a size of 2 inches, which greatly increases the cost of massive production. In this work, a 4-inch crack-free high-power UVC-LED wafer is reported. This achievement relies on a proposed strain-tailored strategy, where a 3D to 2D (3D-2D) transition layer is introduced during the homo-epitaxy of AlN on the high temperature annealed (HTA)-AlN template, which successfully drives the original compressive strain into a tensile one and thus solves the challenge of realizing a high-quality Al 0.6 Ga 0.4 N layer with a flat surface. This smooth Al 0.6 Ga 0.4 N layer is nearly pseudomorphically grown on the strain-tailored HTA-AlN template, leading to 4-inch UVC-LED wafers with outstanding performances. The strategy succeeds in compromising the bottlenecked contradictory in producing a large-sized UVC-LED wafer on pronounced crystalline AlN template: The compressive strain in HTA-AlN allows for a crack-free 4-inch wafer, but at the same time leads to a deterioration of the AlGaN morphology and crystal quality. The launch of 4-inch wafers makes the chip fabrication process of UVC-LEDs match the mature blue one, and will definitely speed up the universal application of UVC-LED in daily life.

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High quality AlGaN grown on ELO AlN/sapphire templates

Cited by 94 publications

References 14 publications

Epitaxial lateral overgrowth of AlN on self-assembled patterned nanorods

Epitaxial lateral overgrowth of AlN on self-assembled patterned nanorods

Nitride Semiconductors

Drive High Power UVC‐LED Wafer into Low‐Cost 4‐Inch Era: Effect of Strain Modulation

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