Characterization of Threading Dislocations in PVT-Grown AlN Substrates via x-Ray Topography and Ray Tracing Simulation

Zhou, Tianyi; Raghothamachar, Balaji; Wu, Fangzhen; Dalmau, Rafael; Moody, Baxter; Craft, S.A.; Schlesser, R.; Dudley, Michael; Sitar, Zlatko

doi:10.1007/s11664-013-2968-2

Cited by 37 publications

(28 citation statements)

References 11 publications

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“…The most complete information about the dislocation behavior in AlN was obtained with using crystals grown by seeded PVT (also called self nucleation) [3,4] and by spontaneous nucleation technology [1]. Presently, these crystals, which are freestanding boules of 10-15 mm in diameter and height, possess the highest structural quality.…”

Section: Introductionmentioning

confidence: 99%

“…Basal plane slip was explained by radial temperature gradients [3]. TD arrays are configured from screw and edge type dislocations [4]. Similar to epitaxial GaN films, the overwhelming majority of TDs are of edge type; however, the density of TDs in AlN is tremendously lower: ≤1 × 10 4 cm −2 .…”

Section: Introductionmentioning

confidence: 99%

“…Peak broadening analysis may give only some general conclusions about prevailing type of dislocations as well as most typical dislocation configurations. Unlike the freestanding boules [1,3], in which the dislocations were successfully examined by topography [4], AlN templates are usually investigated by using both X-ray rocking curves and a wet-chemical etching method [2,7].…”

Section: Introductionmentioning

confidence: 99%

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Distribution of Dislocations near the Interface in AlN Crystals Grown on Evaporated SiC Substrates

Argunova

Gutkin

et al. 2017

Crystals

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Abstract:To exploit unique properties of thin films of group III-nitride semiconductors, the production of native substrates is to be developed. The best choice would be AlN; however, presently available templates on sapphire or SiC substrates are defective. The quality of AlN could be improved by eliminating the substrate during the layer growth. In this paper, we demonstrate freestanding AlN layers fabricated by an SiC substrate evaporation method. Such layers were used to investigate dislocation structures near the former AlN-SiC interface. Specimens were characterized by synchrotron radiation imaging, triple-axis diffractometry and transmission electron microscopy (TEM). We found that the evaporation process under non-optimal conditions affected the dislocation structure. When the growth had been optimized, AlN layers showed a uniform distribution of dislocations. The dislocations tended to constitute low-angle subgrain boundaries, which produced out-of-plane and in-plane tilt angles of about 2-3 arc-min. Similar broadening was observed in both symmetric and asymmetric rocking curves, which proved the presence of edge, screws as well as mixed dislocation content. TEM revealed arrays of edge threading dislocations, but their predominance over the other threading dislocations was not supported by present study. To explain the experimental observations, a theoretical model of the dislocation structure formation is proposed.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Distribution of Dislocations near the Interface in AlN Crystals Grown on Evaporated SiC Substrates

Argunova

Gutkin

et al. 2017

Crystals

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“…The groups employing AlN bulk substrates have mainly followed two approaches to fabricating AlGaN-based LEDs. The problem in growing AlN substrates by physical vapor transport (PVT) [55], which is also referred to as sublimation [56,57], is absorption in the UV region due to carbon [58] and oxygen [59] impurities. The advantage of AlN bulk substrates is high crystallinity with a TDD lower than 10 4 /cm 2 [55,56].…”

Section: Seti Nitekmentioning

confidence: 99%

A Review of AlGaN-Based Deep-Ultraviolet Light-Emitting Diodes on Sapphire

Nagasawa¹,

Hirano²

2018

Applied Sciences

185

111

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This paper reviews the progress of AlGaN-based deep-ultraviolet (DUV) light emitting diodes (LEDs), mainly focusing in the work of the authors’ group. The background to the development of the current device structure on sapphire is described and the reason for using a (0001) sapphire with a miscut angle of 1.0° relative to the m-axis is clarified. Our LEDs incorporate uneven quantum wells (QWs) grown on an AlN template with dense macrosteps. Due to the low threading dislocation density of AlGaN and AlN templates of about 5 × 108/cm2, the number of nonradiative recombination centers is decreased. In addition, the uneven QW show high external quantum efficiency (EQE) and wall-plug efficiency, which are considered to be boosted by the increased internal quantum efficiency (IQE) by enhancing carrier localization adjacent to macrosteps. The achieved LED performance is considered to be sufficient for practical applications. The advantage of the uneven QW is discussed in terms of the EQE and IQE. A DUV-LED die with an output of over 100 mW at 280–300 nm is considered feasible by applying techniques including the encapsulation. In addition, the fundamental achievements of various groups are reviewed for the future improvements of AlGaN-based DUV-LEDs. Finally, the applications of DUV-LEDs are described from an industrial viewpoint. The demonstrations of W/cm2-class irradiation modules are shown for UV curing.

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“…A recent instrument to allow white beam topography of large wafers has been commissioned [8]. Monochromatic beam topography has been performed in the C-station, and results have been published by several User groups [9,10]. As well tests of spherically bent alpha-quartz for use in plasma diagnostics by monochromatic beam topography have been obtained [11].…”

Section: White Beam and Monochromatic Beam X-ray Topographymentioning

confidence: 99%