Growth of AlN single crystalline boules

Herro, Ziad; Zhuang, D.; Schlesser, R.; Sitar, Zlatko

doi:10.1016/j.jcrysgro.2010.04.005

Cited by 105 publications

(87 citation statements)

References 10 publications

(14 reference statements)

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“…At such dislocation densities, X-ray diffraction measurements become almost insensitive due to a weak influence of dislocation strain fields on the angular range of reflection from a rather large volume of crystal. Double-crystal rocking curves taken with 0002 reflection were shown to be very narrow at the top of a freestanding boule: 13 arcs; however, towards the beginning of growth, the peak width increased to 78 arcs due to decreasing uniformity of growth conditions [5].…”

Section: Introductionmentioning

confidence: 95%

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: 95%

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

Argunova

Gutkin

et al. 2017

Crystals

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“…This specimen shape particularly suitable for uniaxial pressure measurements was cut from AlN single crystal wafer material grown by the physical vapor transport method on N-polar c-plane (0001) seeds [25][26][27]. Polar sample surfaces were polished to an optical finish in order to facilitate a homogenous strain distribution throughout the sample after application of uniaxial stress onto the corresponding c-plane surfaces.…”

Section: Methodsmentioning

confidence: 99%

“…[22] for the hydrostatic PPCs due to the employment of high quality bulk AlN crystals. Such bulk AlN well represents most recent crystal growth advances [25,26,33] and even allows the reproducible application of hydrostatic pressures in excess of 20 GPa [22]. Hence, in order to further compare the obtained PDPs a and b with literature values (Tab.…”

Section: Raman Spectroscopy Undermentioning

confidence: 99%

Phonon pressure coefficients and deformation potentials of wurtzite AlN determined by uniaxial pressure-dependent Raman measurements

et al. 2014

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We studied bulk crystals of wurtzite AlN by means of uniaxial pressure-dependent Raman measurements. As a result, we derive the phonon pressure coefficients and deformation potentials for all zone center optical phonon modes. For the A1 and E1 modes we further experimentally determined the uniaxial pressure dependence of their longitudinal optical -transverse optical (LO-TO) splittings. Our experimental approach delivers new insight into the large variance among previously reported phonon deformation potentials, which are predominantly based on heteroepitaxial growth of AlN and the ball-on-ring technique. Additionally, the measured phonon pressure coefficients are compared to their theoretical counterparts obtained by density functional theory implemented in the SIESTA package. Generally, we observe a good agreement between the calculated and measured phonon pressure coefficients but some particular Raman modes exhibit significant discrepancies similar to the case of wurtzite GaN and ZnO, clearly motivating the presented uniaxial pressure-dependent Raman measurements on bulk AlN crystals.

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“…[33] Although there are still challenges, such as contamination from impurities, lack of large-sized AlN seeds, and difficulty in tailoring desired thermal profile inside the growth reactor that hinder the reproducible growth to cite a few, [34] several groups have achieved PVT-grown AlN single crystals with diameters up to 2 inch. [32,[35][36][37][38][39] X-ray rocking curves with a full width at half maximum (FWHM) close to 30 arcsec for both (0002) and (101 2) reflections and etch pit densities (EPDs) below 10 4 cm -2 were reported with an usable area of ~85%. [32] Low dislocation density AlGaN epilayers with both symmetric and asymmetric rocking curves below 100 arcsec have been grown on these AlN wafers.…”

Section: Growth and Optical Properties Of Bulk Aln For Duv Ledsmentioning

confidence: 98%

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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Growth of AlN single crystalline boules

Cited by 105 publications

References 10 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

Phonon pressure coefficients and deformation potentials of wurtzite AlN determined by uniaxial pressure-dependent Raman measurements

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

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