Preparation of Bulk AlN Seeds by Spontaneous Nucleation of Freestanding Crystals

Hartmann, C.; Wollweber, J.; Dittmar, A.; Irmscher, K.; Kwasniewski, Albert; Langhans, Frank; Neugut, Tom; Bickermann, Matthias

doi:10.7567/jjap.52.08ja06

Cited by 75 publications

(68 citation statements)

References 38 publications

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“…The lack of large-area native substrates of high crystalline quality that are lattice matched, chemically compatible and have a similar coefficient of thermal expansion remains a critical issue. Currently, aluminum nitride (AlN) crystals are the most promising substrate materials for the semiconductor and UV LED industry [1,2].…”

Section: Introductionmentioning

confidence: 99%

“…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%

“…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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“…Kinoshita et al 6 demonstrated a deep UV LED with single emission at 268 nm with output power as high as 28 mW fabricated using the HVPE layers. Furthermore, Hartmann et al 7 suggested that oxygen could also play a role in determining the transparency of the crystal, depending on its relative amount with respect to carbon. This result highlights that it is the interplay between native or impurity point defects and their complexes that ultimately determines transparency.…”

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confidence: 99%

Vacancy compensation and related donor-acceptor pair recombination in bulk AlN

Gaddy¹,

Bryan²,

Bryan³

et al. 2013

Applied Physics Letters

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A prominent 2.8 eV emission peak is identified in bulk AlN substrates grown by physical vapor transport. This peak is shown to be related to the carbon concentration in the samples. Density functional theory calculations predict that this emission is caused by a donor-acceptor pair (DAP) recombination between substitutional carbon on the nitrogen site and a nitrogen vacancy. Photoluminescence and photoluminescence-excitation spectroscopy are used to confirm the model and indicate the DAP character of the emission. The interaction between defects provides a pathway to creating ultraviolet-transparent AlN substrates for optoelectronics applications.

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“…The underlying mechanisms for the formation of these bands are still under discussion. [35,39,[44][45][46][47][48][49][50] Specifically, at least three absorption bands at 2.8 eV, 3.3-4.3 eV and 4.7 eV were found and discussed for PVT-grown AlN. The origin of the 2.8 eV band is still an issue of intense debate.…”

Section: Growth and Optical Properties Of Bulk Aln For 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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Preparation of Bulk AlN Seeds by Spontaneous Nucleation of Freestanding Crystals

Cited by 75 publications

References 38 publications

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

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

Vacancy compensation and related donor-acceptor pair recombination in bulk AlN

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

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